Antiretroviral enantiomeric nucleotide analogs

ABSTRACT

Resolved enantiomers of the formula (IA) and (IB)                    
     wherein B is a purine or pyrimidine base or aza and/or deaza analogs thereof are useful in antiviral pharmaceutical compositions to treat retroviral infections.

This application is a 371 of PCT/US93/07360 filed Aug. 4, 1993, which isa continuation-in-part of U.S. application Ser. No. 07/925,610 filedAug. 5, 1992, now U.S. Pat. No. 6,057,305.

FIELD OF THE INVENTION

This invention concerns acyclic nucleotide analogs, their preparationand use. In particular it concerns separate enantiomers of2-phosphonomethoxypropyl derivatives of purine and pyrimidine bases.

BACKGROUND OF THE INVENTION

There is an urgent need for development of chemotherapeutic agents inthe therapy of viral diseases. In particular treatment of diseasescaused by retroviruses presents one of the most difficult challenges inhuman medicine. While a number of antiviral agents which are registeredor are currently under study can effectively cure disease, relievesymptoms or substantially prolong the intervals among the recurrences ofcertain chronic viral infections, such positive outcomes have not yetbeen achieved in many instances, notably that of AIDS, as an example ofretroviral disease. Selectivity of antiviral action, which is animportant requirement for novel antiviral agents, has not been achieved.

Most of the compounds which are clinically useful for antiviralchemotherapy are nucleosides, modified in either the purine orpyrimidine base and/or the carbohydrate moiety. Such compounds mainlyact in processes related to the synthesis of viral nucleic acids; theiraction depends on ability to undergo phosphorylation and subsequenttransformation to the triphosphates. One problem in administeringmodified nucleosides is the absence of suitable phosphorylating activityin the host cell and the existence of viral strains lackingvirus-specific phosphorylating activity. While enzymatically resistantnucleotide analogs might appear to be particularly useful as potentialantivirals, their polar character prevents effective entry of theseanalogs into the cells, as does lack of appropriate nucleotide receptorsat the cellular membrane.

This difficulty appears to be overcome in the series of acyclicnucleotide analogs which contain an aliphatic chain, bearing hydroxylgroups, replacing the sugar moiety. For example, the phosphates orphosphonic acid derivatives derived from the antiviral nucleoside analogganciclovir (Cytovene) are reported to possess an anti-herpes virusactivity (Reist at al., in “Nucleotide Analogs as Antiviral Agents”, ACSSymposium Series, No. 401, pp. 17-34 (1989); Tolman, ibid, pp. 35-50;Prisbe et al., J Med Chem (1986), 29:671).

The following formulas describe several classes of prior art compounds:

Another group of antiviral compounds where the antiviral action is lessstrictly limited by the nature of the heterocyclic base includesphosphonic acid analogs in which a phosphonic acid moiety is linked tothe hydroxyl group of an aliphatic chain sugar substitute via amethylene unit. Examples of such compounds are HPMP-derivatives (1)which were disclosed by the UK Patent Application No. 2 134 907 andPV-3017, now published on Dec. 30, 1986 as EP 206,459 of Holÿ et al.Such compounds act exclusively against DNA viruses as reported by DeClercq et al. in Nature (1986) 3:464-467, and reviewed by Holÿ et al. inAntiviral Res (1990) 13:295.

A similar type of antivirals is represented by PME-derivatives (2)disclosed by European Patent Application 0 206 459 by Holÿ et al. anddescribed in detail by De Clercq at al. in Antiviral Res (1987) 8:261,and by Holÿ et al. in Collection Czech Chem Commun (1987) 52:2801; ibid.(1989), 54:2190). These compounds act against both DNA viruses andretroviruses, including HIV-1 and HIV-2. The adenine derivative, PMEA,was demonstrated to exhibit an outstanding activity against Moloneysarcoma virus in mice, simian immunodeficiency virus in Rhesus monkeysas well as feline immunodeficiency virus in cats (Balzarini et al., AIDS(1991) 5:21; Egberink et al., Proc Natl Acad Sci U.S.A. (1990) 87:3087).

The extensive structure-activity investigation which concentrated on themodification of the side-chain (described by Holÿ et al. in “NucleotideAnalogs as Antiviral Agents”, ACS Symposium Series No.401 (1989), p. 51)did not reveal any additional substantially active antivirals.Replacement of this hydroxyl by fluorine atom resulted in theFPMP-compounds (3) which, in addition to having some anti-DNA-virusactivity display a substantial effect on both HIV-1, HIV-2 and murinesarcoma virus (as taught by Holÿ et al., Czechoslovak Patent ApplicationPV 2047-90 now published on Oct. 30, 1991 as EP 454,127, and byBalzarini et al., Proc Natl Acad Sci U.S.A. (1991) 88:4961).

The racemic mixtures of 9-(2-phosphono-methoxypropyl)adenine and guanine(PMPA and PMPG) were also described by Holÿ et al., European PatentAppl. 0206459 (PMPA) and Holÿ et al., Collection Czech Chem Commun(1988) 53:2753 (PMPA), and by U.S. patent application Ser. No. 932,112(PMPG). PMPA was devoid of any appreciable antiherpetic effect while anyantiherpetic activity of PMPG appeared due to its substantialcytotoxicity. The clinical forms of PMPG, and of the related compound,9-(3-hydroxy-2-(phosphonomethoxy)propyl)guanine (HPMPG) are disclosed inEP application 452935. For these guanine forms, the R-enantiomersconsistently gave greater antiviral activity, especially in regard tothe retrovirus HIV. There was little difference between R&S enantiomersin antiviral activity with regarding to some DNA viruses. It cannot bepredicted whether this pattern of activity would extend to PMP compoundsof other than guanine.

Nothing in the above-cited references or their combination permits anyprediction that the resolved enantiomers of the present invention wouldexhibit antiretroviral activity, or what the enantiomers preferencewould be.

SUMMARY OF THE INVENTION

Resolved enantiomeric forms of N-(2-phosphono-methoxypropyl) derivativesof purine and pyrimidine bases have been synthesized and found topossess useful and unexpected antiviral activity which is directedspecifically against retroviruses. These compounds are of the formulasIA and IB, wherein IA represents the R enantiomer and IB represents theS enantiomer.

In the formulas IA and IB, B is a purine or pyrimidine base or azaand/or deaza analog thereof except for guanine and R is independently H,alkyl(1-6C), aryl or aralkyl.

Thus, in one aspect, the invention is directed to compositionscomprising Formula IA unaccompanied by any substantial amount of thecorresponding compound of Formula IB and to compositions comprising acompound of the Formula IB unaccompanied by any substantial amount ofthe corresponding compound of the formula IA.

By “any substantial amount” is meant less than about 5 mole %,preferably less than about 2 mole %, more preferably less than about 1mole % and most preferably in undetectable amounts. By “correspondingcompound” is meant the enantiomer of the compound shown.

Other aspects of the invention include the preparation of thesecompositions, their formulation into antiviral pharmaceuticalcompositions and the use of these formulations to treat retroviralinfections.

DETAILED DESCRIPTION OF THE INVENTION

The compounds of the invention are the resolved (R) and (S)-enantiomersof N-(2-phosphonomethoxypropyl) derivatives of purine and pyrimidinebases which have structural formula I.

B is a purine or pyrimidine base or an aza and/or deaza analog thereofother than guanine. Renantiames are preferred. As used herein, “purine”refers to substituted or unsubstituted moieties of the formula (in thefollowing, free valences and hydrogen are not shown):

and “pyrimidines” to substituted or unsubstituted moieties of theformula

In aza analogs, at least one C shown in the above formulas is replacedby N; in deaza analogs, at least one N is replaced by C. Combinations ofsuch replacements are also included within the scope of the invention.

Thus, 1-deaza purine analogs are of the formula

3-deaza purine analogues are of the formula

8-aza purine analogs are of the formula

1-deaza-8-aza purine analogs are of the formula

Preferred embodiments of B are those wherein B is a purine base selectedfrom the group consisting of adenine, 2,6-diaminopurine, 2-aminopurine,hypoxanthine, xanthine; and their 1-deaza, 3-deaza or 8-aza analogs; and

derivatives of purine or said analogs, which derivatives are other thanguanine, substituted at position 2 and/or 6 and/or 8 by amino, halogen,hydroxy, alkoxy, alkylamino, dialkylamino, aralkylamino,heteroaralkylamino, hydroxyamino, alkoxyamino, hydrazino, heterocyclicamino, azido, mercapto or alkylthio.

For the purposes herein it is understood that tautomeric forms areincluded in the recitation of a given group, e.g., thio/mercapto oroxo/hydroxyl.

Included in this invention are those embodiments wherein B is apyrimidine base selected from the group consisting of cytosine, uracil,thymine, 5-methylcytosine, and their 6-aza analogs; and

derivatives of pyrimidine substituted at the exocyclic amino group inposition 4 by alkyl, aralkyl, hydroxy or amino.

As used herein, halogen refers to F, Cl, Br or I; alkyl refers to astraight- or branched-chain saturated hydrocarbyl group containing 1-6C,such as methyl, ethyl, 2-propyl, n-pentyl, neopentyl and the like;alkoxy is a group of the formula —OR₁ wherein R₁ is alkyl as abovedefined; alkylthio is a group of the formula —SR₁ wherein R₁ is alkyl asabove defined; aralkyl or heteroaralkyl is a group of the formula —R₁—Arwherein —R₁— is the alkylene counterpart of alkyl(—R₁) as above defined,Ar is a substituted (with hydroxyl, halo, amino, sulfonyl, carbonyl orC1-C3 alkyl substituted with hydroxyl, halo, amino, sulfonyl orcarbonyl) or unsubstituted aromatic group having 6-10C and optionally aheteroatom selected from oxygen or nitrogen, e.g., phenyl, napthyl,quinolyl and benzyl; aralkyl amino or heteroaralkyl amino means groupsof the formula —N(Z)₂ wherein Z independently is H or —R₁—Ar (but atleast 1 Z is —R₁—Ar); heterocyclic amino is a saturated or unsaturatedheterocyclic ring containing at least 1 N atom (ordinarily 1) andoptionally in addition at least 1 other heteroatom (examples beingpyrrolidine, morpholino, piperidine and the like radicals). Typically,cyclic structures contain from 3 to 6 ring atoms and are monocyclic. Insome embodiments, the substituents of purine 6-amino groups are takentogether with purine N₁ to form an N-heterocycle fused to the purinylmoiety, for example as in N1, N6-etheno-adenine.

The compounds of the invention can be isolated in the form of freeacids, salts or, in the case of compounds with heterocyclic basesbearing at least one amino function, in the form of zwitterions. Theacid or zwitterionic forms can be obtained on purification of thedeionized crude material by anion exchange chromatography, usingvolatile organic acids (acetic or formic acid) as eluents. The free acidforms can be easily transformed into physiologically acceptable salts bymethods known in the art. Such salts include those of ammonium ion, Li⁺,Na⁺, K⁺, Mg⁺⁺ and Ca⁺⁺ or pharmaceutically acceptable organic cations;the salts may be monobasic or dibasic. Compounds with at least one aminofunction contained in B can also be prepared as the acid addition saltsinorganic or organic acids, such as HBr, HCl, H₂SO₄ or HOAc.

In certain cases, the acid or zwitterionic forms of compounds of theFormula IA and IB are extremely water-insoluble. Under suchcircumstances, purification is performed on a medium basic anionexchanger (e.g., DEAE-cellulose, DEAE-Sephadex) in a weakly alkalinevolatile buffer, such as triethylammonium hydrogen carbonate. Theresulting water-soluble triethylammonium salts can be transformed tosalts of other cations by, e.g., cation exchange, using cation exchangerin the corresponding form.

The free acids, zwitterions or salts of compounds of Formula IA or IBare stable in the solid state or in sterile aqueous or aqueous-alcoholicsolutions.

Methods of Preparation

The compounds of this invention can be prepared from an easily preparedchiral intermediate X derived from resolved lactic acid esterenantiomers using reaction scheme 1 or 2.

Reaction scheme 1 is as follows:

wherein B is as defined above and B′ is its suitably protected form;the * above the chiral center indicates that the resolved enantiomer isused.

Protection of B comprises blocking of active hydrogen atoms contained inB, such as any hydroxy, amino or carbamido group. Protection can beachieved by introduction of alkali-labile groups, such as acetyl,benzoyl, pivaloyl or amidine, such as a dimethylaminomethylene group,or, by acid-labile groups such as trityl, substituted trityl,tetrahydropyranyl groups and the like.

The desired enantiomer of 2-O-tetrahydro-pyranylpropane-1,2-diol of theFormula X is transformed to the corresponding 1-O-p-toluenesulfonylesters in Step 1 under usual conditions, i.e. reaction withp-toluenesulfonyl chloride in pyridine. The tosyl group shown ispreferred, however standard organic leaving groups such as mesylate,triflate or halide can also be used.

The protected intermediate of the Formula XI, isolated either by directcrystallization or by silica gel chromatography, occurs as a mixture ofdiastereomers which gives complex NMR spectra.

The alkylation of a heterocyclic base with the synthon of the Formula XIin Step 2 is mediated by the formation of an anion which can begenerated either by pretreatment of the base with alkali hydride in aninert solvent, such as dimethylformamide, or, by the anion formationgenerated in situ by alkali carbonate. In the latter case, an importanceof cesium carbonate as a catalyst must be recognized. This catalyst notonly substantially accelerates the alkylation of the base, it alsofavorably influences the regiospecificity of alkylation by the synthonXI in purine ring systems, giving alkylation at the preferred N9position of purines or the corresponding position in the aza or deazabases.

The tetrahydropyran-2-yl group is cleaved in acidic media to afford theintermediate III in Step 3. This cleavage can be achieved by the actionof mineral acid (e.g. sulfuric acid) anion exchange resins or organicacids (e.g. acetic acid, formic acid) followed by deionization.

The N-(2-hydroxypropyl) derivatives of Formula III are transformed inStep 4 to base-protected derivatives of Formula V using any of a varietyof methods generally available for the purpose, such as selectiveN-acetylation, N-benzoylation, reaction with dimethyformamide dialkylacetals, N-tritylation, reaction with 3,4-dihydro-2H-pyrane and thelike.

In Step 5 of Scheme 1 the protected intermediate of Formula V isconverted to the alkoxide anion by treatment with a suitable base, suchas alkali metal hydride, in a non-reactive solvent, such asdimethylformamide, and the alkoxide is treated with dialkylp-toluenesulfonyloxymethylphosphonate (Formula IV). Preferably thephosphonate esters are of 2-propyl alcohol. The reaction is performed bystirring a mixture of the Formula V intermediate with the tosylderivative of Formula IV in the presence of three, equivalents (relativeto intermediate V) of alkali hydride, e.g., NaH or KH or other suitablereagents at temperatures ranging from −10° to 80° C., mostly from 0° C.to 20° C. The reaction lasts from several hours up to several days,depending on the nature and concentration of the reaction components.Since gaseous hydrogen is evolved during the reaction, it is essentialto work in an open system with suitable protection against moisture.

Protecting groups are then removed from B′ and the phosphonate esterlinkages are hydrolyzed. Removal of the protecting groups from B′ inStep 6 can be achieved by generally acceptable methods such asmethanolysis, acid hydrolysis, etc. Alkali labile groups can be removedsimply by dilution of the mixture with methanol. The resulting diesterof Formula VII is isolated by silica gel chromatography, or using othersuitable supports, or contaminating non-nucleotide materials may beremoved by deionization on cation exchangers, such as Dowex 50, or, byhydrophobic silica chromatography. The purified intermediate of FormulaVII is then hydrolyzed, in Step 7 for example, by treating with ahalotrialkylsilane, such as bromotrimethylsilane or iodotrimethylsilanein a polar aprotic solvent such as acetonitrile or DMF for 4-20 hours atroom temperature. Volatiles are then evaporated in vacuo and the finalproduct may then be obtained by further purification and isolationtechniques depending upon its character. Ion exchange chromatographymaking use of the presence of negatively charged phosphonate group ispreferred.

Alternatively, compounds of Formula I can be prepared by Reaction Scheme2.

In Scheme 2, the synthon of Formula XVII is ultimately used to providethe chiral PMP precursor. It bears a leaving tosyl group and can be usedfor alkylation of the heterocyclic base or its protected derivative toafford Formula VII, the protected diester form of the compounds of theinvention.

In Reaction Scheme 2, as in Reaction Scheme 1, a resolved form of2-O-(tetrahydropyranyl)-propane-1,2-diol of the Formula X provides therequired resolved enantiomer. The resolved compound of Formula Xaffords, in Step 1, on benzylation under standard conditions, e.g. withbenzyl bromide in the presence of sodium hydride in DMF, the benzylether XII which is then transformed by acid hydrolysis in Step 2 to theresolved enantiomeric 2-O-benzylpropane-1,2-diol of the Formula XIII.Either enantiomer (a distillable oil) affords, in Step 3, onchloromethylation with 1,3,5-trioxane or paraformaldehyde in thepresence of hydrogen chloride an intermediary chloromethyl ether of theFormula XIV which is, without purification, transformed in Step 4 intothe phosphonate diester XV by heating with tri(2-propyl)phosphite withsimultaneous removal of 2-propyl chloride. Though the intermediate ofthe Formula XV is distillable in a high vacuum, this procedure mayresult in racemization. Partially purified products of this reaction arethen hydrogenolysed under standard conditions such as hydrogenation inthe presence of palladium-on-charcoal catalyst in methanol and theintermediary diester of the Formula XVI resulting from Step 5 is,without isolation, transformed in Step 6 into the tosyl derivative XVIIby the action of tosyl chloride in pyridine.

The sequence X→XVII involves six steps, but does not requirepurification of the intermediates. All reactions proceed with highconversion so that the over-all yield of the sequence exceeds 40%.2-propyl esters of the phosphonate are preferred, but other phosphonateprotecting ester groups such as methyl, ethyl, benzyl and cyclicdiesters can be used to the same effect. Also the tosyl group in thesynthon of the Formula XVII could be replaced by other leaving groups,as for example mesyl, triflyl, p-nitrophenylsulfonyl, etc.

Step 7 of this synthetic sequence consists in the alkylation of theheterocyclic base by the synthon of the Formula XVII. It requires anequimolar amount of the base relative to the heterocycle. The alkylationis best performed in DMF at increased temperature with either a sodiumsalt generated from the heterocyclic base by sodium hydride reaction or,alternatively, with a mixture of the heterocyclic base and a slightexcess of potassium carbonate or, to an advantage, cesium carbonate. Thereaction can be made either with unprotected or protected (e.g.N-benzoylated) bases or their precursors as mentioned in the descriptionof the reaction according to the Scheme 1.

The protected intermediates of the Formula VI can be applied toadvantage for transformations at the heterocyclic base to afford a widevariety of additional compounds of the Formula I. The reactivity of thehalogen (e.g. chlorine) atom at position 6 of the2-amino-6-chloropurine, derivative'of the Formula VII is applicable forthe preparation of a wide variety of 6-substituted 2-aminopurinecompounds; thus, by heating with sodium or lithium azide it is possibleto prepare the 2-amino-6-azidopurine derivative which can be furtherreduced to the 2,6-diaminopurine compound. Alternatively, treatment ofthe chloro derivative with thiourea affords the 6-thioguanine compound,whereas its reaction with primary or secondary amines providesN6-substituted or disubstituted 2,6-diaminopurine derivatives.

An analogous transformation is applicable also to the diester of theFormula VI derived from 6-chloropurine where it leads ultimately to thecompounds of the Formula I containing 6-mercaptopurine or N6-mono- ordisubstituted adenine.

The alkylation proceeds rapidly and the required intermediate of theFormula VII can be easily isolated from the reaction mixture andpurified by chromatography. Further processing of these intermediatesleading to the compounds of the Formula IA and IB is identical with theprocedure described in the Scheme 1.

An advantage of this method of preparation of the Formula I compoundsover the method described by the Scheme 1 consists, in addition to thepossible avoidance of base protection, in the elimination of acidicconditions which are essential for the preparation of the intermediaryN-(2-hydroxypropyl) derivatives of the Formula II, as well as of anyother deprotection except for ultimate halotrimethylsilane treatment.The alternative procedure can thus be applied for the syntheses ofcompounds of the Formula I bearing sensitive heterocyclic bases.

In respect to both reaction Schemes 1 and 2, the compounds of theinvention may be prepared by alkylation of the desired heterocyclic baseB as shown, or, in certain cases, by alkylation of a precursor of B.Thus, guanine derivatives can be best synthesized via alkylation of2-amino-6-chloropurine followed by acid hydrolysis of the C—Cl linkage.Cytosine derivatives can be synthesized by direct alkylation of cytosinein the presence of cesium carbonate in a modest yield; better yields areobtained by the ammonclysis of an intermediate formed by alkylation of4-methoxy-2-pyrimidone with synthon XI.

Similar subsequent changes at the heterocyclic base can be performedwith the final products of the Scheme, i.e. the compounds of Formula Iwhich are the subjects of the invention: adenine, 2,6-diaminopurine orguanine derivatives can be transformed by deamination with nitrous acidor its esters to the corresponding hypoxanthine, 2-hydroxyadenine orxanthine derivatives; similarly, uracil derivatives can similarly beconverted to cytosine derivatives. Further transformations of thecompounds of the Formula I can be realized with routine methods ofnucleic acid chemistry: e.g., reaction of the adenine moiety withchloroacetaldehyde will afford the N1,6-etheno derivatives; brominationof purine base to obtain the 8-bromo derivatives; N-alkylation of theNH— functions in both the purine and pyrimidine compounds, etc. None ofthese subsequent transformations concerns any changes at the side chainor the phosphonate group of the compounds of Formula I.

It will be recognized that the intermediate compounds that are parts ofthe pathways of Schemes 1 and 2 are themselves novel compounds andtherefore are part of the invention.

An advantage of using the processes of Schemes 1 and 2 consists in theutilization of starting materials of the Formula X, which are easilyavailable in optically pure forms. The reaction sequence to prepare thechiral synthon X used both in Scheme 1 and Scheme 2 is described inScheme 3.

The crucial step of every asymmetric synthesis depends on theavailability of optically pure chiral starting materials. The methodused in the present invention makes use of commercially available(Merck) enantiomers of lactic acid alkyl esters of Formula VIII. Theseesters are first protected at the hydroxyl function by tetrahydropyranylgroup; this reaction is performed without solvent by direct addition inthe presence of an acid catalyst. The esters of the Formula IX areobtained by fractionation in vacuo. These intermediates are reduced bylithium aluminum hydride in ether or by bis(2-methoxyethoxy)aluminumhydride in ether or other inert solvents to the compounds of Formula X.

Biological Activity and Uses

The enantiomerically resolved compounds of the invention displaysignificant antiretroviral activity both in vitro and in vivo. Their invitro efficacy was demonstrated on human immunodeficiency virus type 1(HIV-1) and type 2 (HIV-2) in MT4 and CEM cells, as well as on Moloneymurine sarcoma virus (MSV) in C3H/3T3 cells. Their in vivo efficacy wasproven in MSV infected NMRI mice, where the compounds markedly postponedthe mean day of tumor initiation and substantially prolonged the meansurvival day, both upon parenteral and oral administration.

The compounds of the invention have several advantages over theprototype compounds (PMEA, PMEADAP, PMEG) and/or FPMP derivatives, e.g.,FPMPA, FPMP-DAP), and most relevant, unresolved PMPG+PMPA: (a) theirantiretroviral activity is clearly separated from other antiviralactivities (e.g. against herpes viruses); (b) their antiretroviralactivity is not due to cellular toxicity. Consequently, the in vitrotherapeutic index of these compounds is much higher than those of theprototype compounds and reaches a value of >2000 in some of the cases.Such compounds can be ideally suited to a long-term treatment of chronicdiseases, e. g. AIDS.

The structures of the test compounds presenting the subject of thisinvention are completely unrelated to any of the compounds currentlyused in clinical trials of AIDS patients. This will avoidcross-resistance of these compounds against those virus strains thatbecame resistant to such treatment, e.g., AZT, DDI, DDC, TIBO,nevirapine, pyridinohe, etc.

The biological activity of these compounds is highly enantiospecific.Generally, the (R)-enantiomers are responsible for the antiretroviralactivity. The activity of (S)-enantiomers in the guanine series isaccompanied by a substantially increased toxicity.

The compounds of the invention can be applied for the treatment ofdiseases caused by retroviruses, e.g. human immunodeficiency viruses(AIDS), human T-cell leukemia virus (hairy cell leukemia, acute T-cellleukemia (HTL)). Since the molecular target of antiviral action of thesecompounds is the virus-encoded reverse transcriptase, they should alsohave anti-hepadna virus activity (e.g. hepatitis B virus).

The compounds of this invention also are useful as intermediates in thepreparation of other compounds useful in in vitro methods. For example,the compounds containing bases capable of Watson-Crick base pairing arediphosphorylated by known methods and employed as analogues to dideoxyNTP's heretofore conventionally used in nucleic acid sequencing. Thecompounds of this invention function as nucleic acid chain terminators,as do dideoxy NTPS. Other uses based on this property will be apparentto the ordinary artisan.

The compounds of this invention also are useful in preparative ordiagnostic methods based on oligonucleotide or nucleic acidhybridization. For example, the compounds are converted to monomerssuitable for incorporation into oligonucleotides using non-enzymaticsynthetic methods, e.g. H-phosphonate or phosphoramidite chemistries.The monomers then are used as the 3′ terminal base in oligonucleotidesynthesis using such methods. The PMP portion of the monomer, anymodified base present in the monomer, or both are readily available forrecognition and binding by an antibody. The antibody in turn is labelled(for detecting hybridization of monomer-labelled probe to a targetanalyte sequence or the antibody is immobilized (for preparativeseparation of probe-bound nucleic acid). Exemplary methods of this sortare further described in EP 144,913,; EP 146,039; WO 85/02415,; UK2,125,964A; they do not require that the monomers of this invention becapable of Watson-Crick base-pairing or that they be recognized by anypolymerase.

The compounds may be administered topically or systemically i.e. orally,rectally, intravaginally and parenterally (by intermuscular,intravenous, subcutaneous and nasal routes). Generally, the oralapplication will require a larger quantity of the active ingredient toproduce a therapeutic effect comparable with quantity givenparenterally.

Pharmaceutical compositions for the treatment of human retroviraldiseases will comprise at least one compound of the Formula IA or IB ora pharmaceutically acceptable salt thereof, generally comprising 95 to0.5% wt/wt of the composition in combination with a pharmaceuticallyacceptable carrier and non-toxic inert adjuvant. Other therapeuticagents can also be present. Additionally, mixtures of compounds offormulas IA and/or IB can be employed, provided that each member of suchmixture is substantially free of its enantiomer.

Pharmaceutical compositions containing compounds of the Formula I areconventionally prepared as tablets, lozenges, capsules, powders, aqueousor oil suspensions, syrups and aqueous solutions. The compounds can beformulated for a variety of modes of administration includingsystematic, topical or localized administration. Techniques andformulations generally may be found in Remington's PharmaceuticalSciences, Mack Publishing Co., Easton, Pa., latest edition. The activeingredient is generally combined with a carrier such as a diluentorexcipient which may include fillers, extenders, binders, wettingagents, disintegrants, surface-active agents, or lubricants, dependingon the nature of the mode of administration and dosage forms. Typicaldosage forms include tablets, powders, liquid preparations includingsuspensions, emulsions and solutions, granules, capsules andsuppositories, as well as liquid preparations for injections, includingliposome preparations.

For systemic administration, injection is preferred, includingtransmuscular, intravenous, intraperitoneal, and subcutaneous. Forinjection, the compounds of the invention are formulated in liquidsolutions, preferably in physiologically compatible buffers such asHank's solution or Ringer's solution. In addition, the compounds may beformulated in solid form and redissolved or suspended immediately priorto use. Lyophilized forms are also included. Systematic administrationalso can be by transmucosal or transdermal means, or the compounds canbe administered orally. For transmucosal or transdermal administration,penetrants appropriate to the barrier to be permeated are used in theformulation. Such penetrants are generally known in the art, andinclude, for example, bile salts and fusidic acid derivatives fortransmucosal administration. In addition, detergents may be used tofacilitate permeation. Transmucosal administration may be through use ofnasal sprays, for example, or suppositories. For oral administration,the compounds are formulated into conventional oral administration formssuch as capsules, tablets, and tonics.

For topical administration, the compounds of the invention areformulated into ointments, salves, gels, or creams, as is generallyknown in the art. The compounds may also be administered for ophthalmicor ocular indications when appropriately formulated.

The effective dose of active compound of the present invention isexpected to be about 0.01-50 mg/kg body weight with preferred range of 1to 20 mg/kg. The dosage in clinical applications must be professionallyadjusted considering age, weight and condition of the patient, the routeof administration, the nature and gravity of the illness. Generally, thepreparations are expected to be administered by oral route from about100 mg to about 1000 mg per day, one to three times a day.

The compounds of the invention, their methods of preparation and theirbiological activity will appear more clearly from the examination of thefollowing examples which are presented as an illustration only and arenot to be considered as limiting the invention in its scope. All meltingpoints have been estimated with the use of Kofler's block and areuncorrected. Solutions were evaporated at 40° C./2 kPa when notspecified. Thin-layer chromatography was made with the use of silicaplates containing fluorescent indicator; detection by UV-light. Thenuclear magnetic resonance (NMR) spectral characteristics refer tochemical shifts (δ) expressed in parts per million (ppm) vs.tetramethylsilane (TMS) as reference compound. The multiplicity ofsignals is reported as singlet (s), doublet (d), doublet of doublets(dd), multiplet (m), triplet (t) or quartet (q); other abbreviationsinclude broad (br) signal, aromatic protons (arom.), d₆-DMSO forhexadeuteriodimethylsulfoxide, D₂O for deuterium oxide, NaOD for sodiumdeuteride and CDCl₃ for deuteriochloroform. Other abbreviations areconventional.

The following examples are intended to illustrate but not to limit theinvention.

I. Synthesis of Intermediates of Formula II

A. Resolved Formula XI Precursors

EXAMPLE 1(R)-2-O-Tetrahydropyranyl-1-O-p-toluenesulfonylpropane-1,2-diol

A mixture of isobutyl (R)-lactate (73 g, 0.5 mol, Merck) and3,4-dihydro-2H-pyran (70 g, 0.83 mol, Merck) was treated with 5Mhydrogen chloride in dimethylformamide (4 ml) and set aside at ambienttemperature overnight in calcium chloride protected 250 ml round-bottomflask. Silver oxide (15 g) was added, the mixture stirred magneticallyfor 2 hours and then filtered. The product was isolated by distillation(13 Pa, b.p. 94∝96° C.) to provide isobutyl2-O-tetrahydropyranyl-(R)-lactate (102.5 g, 89%) as a colorless oil.

A 1 l 3-necked round-bottomed flask was oven dried and equipped withreflux condenser with calcium chloride protection tube, 250 ml droppingfunnel and magnetic stirring rod. It was then charged with a suspensionof lithium aluminum hydride (15.8 g, 0.415 mol) and ether (500 ml,distilled from phosphorus pentoxide) and placed in ice-water bath.

A solution of isobutyl 2-O-tetrahydropyrany-(R)-lactate was addeddropwise under stirring at such a speed that the mixture wascontinuously in mild reflux (approx.30 min.). The cooling bath wasremoved and the mixture stirred in reflux for additional 3 hours byapplying an external heating. It was then cooled again by ice-water bathand ethyl acetate (75 ml) was added during 20 minutes followed by water(15 ml) and 4M NaOH (15 ml). The resulting mixture was then filtered bysuction over a layer of Celite 521 (Janssen) and washed with chloroform(500 ml). The combined filtrate was taken down in vacuo, the residueredissolved in ether (300 ml) and anhydrous magnesium sulfate (50 g)added. After standing overnight at ambient temperature, the mixture wasfiltered by suction, washed with ether (200 ml) and the filtratestripped of the solvent in vacuo. The remaining oil afforded bydistillation (13 Pa, 75-76° C.)2-O-tetrahydropyranyl-(R)-propane-1,2-diol (67.5 g, 0.422 mol. 95%) as acolorless oil.

A solution of 2-O-tetrahydropyrany-(R)-propane-1,2-diol(67.2 g, 0.42mol) in pyridine (600 ml) was placed in a 2 l round-bottom flask withmagnetic stirring rod and 500 ml dropping funnel with a side-tubing,protected by calcium chloride tube. 4-Dimethylaminopyridine (2 g) wasadded, the flask was placed in an ice-water cooling bath and a solutionof p-toluenesulfonyl chloride (91 g, 0.477 mol) in pyridine (300 ml) wasadded over 1 hour under stirring. The mixture was stirred underice-cooling for additional 3 hours and left to stand overnight in arefrigerator at 4° C. Water (20 ml) was then added to the mixture and,after standing for 1 hour, pyridine (approx. 300 ml) was distilled offin vacuo. The residue was diluted by ethyl acetate (2.5 l) and shakenwith water (300 ml). After separation of the lower aqueous layer, theorganic phase was washed with water (two 300 ml portions), evaporated invacuo and the residue co-evaporated with toluene (four 250-ml-portions)in vacuo. The remaining amber oil was purified by chromatography oversilica gel (eluting with chloroform) to afford 122 g (0.39 mol, 93%) of(R)-2-O-tetrahydropyrany-1-O-p-toluenesulfonylpropane-1,2 diol as athick colorless oil, R_(F) 0.60 (TLC, chloroform). This product wasstored at +4° C. for several months without obvious decomposition. ForC₁₅H₂₂OS (MW 314,4) calculated: C,57.30; H,7.05; S,10.20. Found:C,57.15; H,7.22; S,10.52.

EXAMPLE 2(S)-2-O-Tetrahydropyranyl-1-O-p-toluenesulfonylproyane-1,2-diol

A mixture of ethyl L-(−)lactate (59 g, 0.5 mol, Merck) and3,4-dihydro-2H-pyran (70 g, 0.83 mol) was treated and worked up exactlyas described in Example 1 to afford, after distillation (2 kPa, 102-104°C.) ethyl 2-O-tetrahydropyrany-(S)-lactate (98 g, 0.485 mol, 97%) as acolorless oil.

This material (91 g, 0.45 mol) was treated with lithium aluminum hydrideas described in Example 2 to afford after distillation (13 Pa, 72-75°C.) 2-O-tetrahydropyrany-(S)-propane-1,2-diol (67.7 g, 0.423 mol, 94%)as a colorless oil.

Following the conditions described in Example1,2-O-tetrahydropyrany-(S)-propane-1,2-diol (67.2 g, 0.42 mol) wastransformed in(S)-2-O-tetrahydropyrany-1-O-p-toluenesulfonylpropane-1,2-diol. Thepurification by chromatography on silica gel (elution by chloroform)gave the product (121 g, 0.386 mol, 92%) as a thick colorless oil,chromatographically (TLC, R_(F) 0.60 in chloroform) homogeneous. ForC₁₅H₂₂O₅S (MW 314,4) calculated: C,57.30; H,7.05; S,10.20. Found:C,57.50; H,7.33; S,9.95.

B. Formula II Compounds

EXAMPLE 3 9-(S)-(2-Hydroxypropyl)adenine

A suspension of finely ground adenine (13.6 g; 0.1 mol) and cesiumcarbonate (16.4 g; 0.05 mol) in dimethylformamide (400 ml, distilledfrom phosphorus pentoxide) was placed in 1 l round-bottom flask equippedwith 250 ml dropping funnel and calcium chloride protecting tube. Themixture was preheated at 100° C. and a solution of(S)-(2-O-tetrahydropyrany-1-O-p-toluenesulfonyl)propane-1,2-diol (31.4g, 0.1 mol) in dimethylformamide (200 ml) was added dropwise undermagnetic stirring over 30 minute period. The resulting clear solutionwas heated at 100° C. for additional 6 hours, cooled down and thesolvent distilled off at 50° C./13 Pa. The residue was extracted withboiling chloroform (three 300-ml-portions), filtered and the filtratetaken down in vacuo. The residue afforded by crystallization fromboiling ethanol 9-(S)-(2-O-tetrahydropyranyloxypropyl)adenine (13.2 g,0.048 mol, 48%) m.p. 172° C. R_(F) 0.40 (TLC, chloroform-methanol, 4:1).For C₁₃H₁₉N₅O₂ (277.3) calc. C, 56.30; H, 6.91; N, 25.26. found C,56.46; H, 6.82; N, 25.57. ¹H-NMR (200 MHz, d6-DMSO): H2,H8 : 2×s, 8.14and 8.04; NH2: br s, 7.20; 1′-CH₂: dd, 1H, 4.23 (J1,2=3.2, Jgem=13.7)and dd, 1H, 4.11 (J1,2=7.1): 2′-CH: m, 1H, 4.06; 3′-CH₃: d, 3H, 1.12(J3,2=6.1); tetrahydropyranyl 1″-CH: dd, 1H, 4.28 (J=2.9, 4.4); 5-CH₂:ddd, 1H, 3.72 (J=3.9, 7.8, 11.5) and ddd, 1H, 3.34 (J=4.9, 5.1, 11.2);additional CH₂: m, 6H, 1.20-1.65.

A solution of 9-(S)-(2-O-tetrahydropyranyloxypropyl)adenine (13 g, 0.047mol) in 0.25M sulfuric acid (300 ml) was left to stand overnight atambient temperature and neutralized with saturated aqueous bariumhydroxide solution to pH 7.0-7.1 (with the use of pH-meter). Theresulting suspension was brought to 80° C. and after standing for 30minutes filtered through a layer of Celite 521 (Janssen) and theprecipitate washed with boiling water (500 ml). The combined filtrateand washings were evaporated to dryness in vacuo, the residuecoevaporated with ethanol (two 200 ml portions and crystallized fromboiling ethanol (ether added to turbidity). The product was collected byfiltration to give 9-(S)-(2-hydroxypropyl)adenine (7.7 g, 0.04 mol,85%), m.p.202° C. For C₈H₁₁N₅O (MW 193,2) calc.: C, 49.73; H, 5.74; N,36.25. found C, 49.59; H, 5.54; N, 36.29. [α]_(D)=−41.0° (c=0.5, 0.1MHCl). ¹H-NMR (200 MHz, d₆-DMSO): H2,H8:2×s, 2H, 8.14 and 8.05; NH₂: brs, 2H, 7.23; OH: br,1H, 5.05 (J_(OH,CH)=4.2); N—CH₂+O—CH: m, 3H,3.97-4.13; CH₃: d, 3H, 1.06 (J_(CH3,CH)=5.6).

EXAMPLE 4 9-(R)-(2-Hydroxypropyl)adenine

The condensation of adenine (13.6 g, 0.1 mol) and(R)-(2-O-tetrahydropyrany-1-O-p-toluenesulfonylpropane-1,2-diol (31.4 g,0.1 mol) was performed in the presence of cesium carbonate (16.4 g, 0.05mol) as described in Example 3. After extraction by boiling chloroform,the crystallization of the residue from ethanol (ether added toturbidity) afforded 9-(R)-(2-O-tetrahydropyranyloxypropyl)adenine (14.6g, 0.053 mol, 53%), m.p.171-172° C. For C₁₃H₁₉N₅O₂ (277.3) calc. C,16.30; H, 6.91; N, 25.26. found C, 56.57; H, 6.71; N, 25.41. ¹H-NMRspectrum (200 MHz, d₆-DMSO) closely resembles to that of9-(S)-(2-tetrahydropyranyloxypropyl)adenine (Example 3).

A solution of 9-(R)-(2-tetrahydropyranyloxypropyl)adenine (14.0 g, 0.05mol) in 0.25 M sulfuric acid was left to stand overnight at ambienttemperature and worked-up as described in Example 3. The product wasisolated to give 9-(R)-(2-hydroxypropyl)adenine (8.1 g, 0.042 mol, 84%),m.p. 202° C. For C₈H₁₁N₅O (MW 193,2) calc. C, 49.73; H, 5.74; N, 36.25.found C, 49.80; H, 5.64; N, 36.44. ¹H-NMR spectrum (200 MHz, d₆-DMSO) isidentical with that of the (S)-enantiomer (Example 9). [α]_(D)=+40.8°(c=0.5, 0.1M HCl).

EXAMPLE 5

9-(R)-(2-hydroxypropyl)-2,6-diaminopurine

A suspension od 2,6-diaminopurine (15 g, 0.1 mol) and cesium carbonate(16.4 g, 0.05 mol) in dimethylformamide (250 ml) was placed in 500 mlround-bottom flask with magnetic stirring rod and calcium chlorideprotecting tube and preheated to 100° C.(R)-(2-O-tetrahydropyrany-1-O-p-toluenesulfonylpropane-1,2-diol (32.8 g,0.104 mol) was added in one portion and the mixture stirred at 100° C.for 20 hours. The solvent was evaporated at 50° C./13 Pa and the residueextracted with boiling chloroform (three 300-ml-portions). The filtratewas separated on silica gel column (500 ml), the product eluted bychloroform-methanol mixture (95:5), affording, after crystallizationfrom ethyl acetate (ether added to turbidity),9-(R)-(2-tetrahydropyranyloxypropyl)-2,6-diaminopurine (14.2 g, 0.0485mol, 48.5%), m.p.150-152° C. For C₁₃H₂₀N₆O₂ (292.3) calc. C, 53.41; H,6.90; N, 28.76. found C, 53.27; H, 7.02; N, 28.77.

A solution of 9-(R)-(2-tetrahydropyranyloxypropyl)-2,6-diaminopurine(11.7 g, 0.04 mol) in 0.25M sulfuric acid (400 ml) was left to standovernight at ambient temperature, neutralized with aqueous ammonia andconcentrated in vacuo. The solution was applied onto a column of Dowex50x8 (250 ml, 100-200 mesh, acid form) and the column washed with wateruntil the UV-absorption and conductivity of the eluate dropped to theoriginal values. The product was eluted by diluted (1:10) aqueousammonia, the UV-absorbing eluate was collected and taken down in vacuo.The residue gave on crystallization from ethanol9-(R)-(2-hydroxypropyl)-2,6-diaminopurine (6.5 g, 0.031 mol, 77.5%),m.p. 192° C. For C₈H₁₂N₆O (208.2) calc. C, 46.15; H, 5.81; N, 40.37.found C, 45.97; H, 5.72; N, 40.56. ¹H-NHR-spectrum (200 MHz, d₆-DMSO):H-8, 1H, 7.62; NH₂: 2×br s, 2×2H, 6.65 and 5.77; OH: br, 1H, 5.05;1′-CH₂: dd, 1H, 3.90 (J_(1,2)=3.9, J_(gem)=13.7) and 3.80, dd 1H(J_(1,2)=7.6, J_(gem)=13.7); 2′-CH: m, 1H, 3.95; 3′-CH₃: d, 3H, 1.04(J_(3,2)=6,19). [α]_(D)=−40.7° (c=0.5, 0.1M HCl).

EXAMPLE 6 9-(S)-(2-Hydroxypropyl)-2,6-diaminopurine

The synthesis was performed in analogy to Example 5, with(S)-2-O-tetrahydropyrany-1-O-p-toluenesulfonylpropane-1,2-diol (34.5 g,0.11 mol). The crude reaction product was dissolved in 0.25 M sulfuricacid (300 ml) and left to stand overnight at ambient temperature. Themixture was alkalized by ammonia and evaporated in vacuo to a volume ofapprox. 150 ml which was then applied onto a column (300 ml, 100-200mesh) of Dowex 50x8 (acid form). The column was washed thoroughly withwater till the disappearance of UV-absorption of the eluate. Subsequentelution with dilute (1:10) ammonia afforded UV-absorbing fraction whichwas taken down in vacuo and crystallized from methanol to give crude9-(S)-(2-hydroxypropyl)-2,6-diaminopurine (content, >95%; 9.2 g, 0.044mol, 44%) which was used in the subsequent synthetic step.[α]_(D)=+41.2° (c=0.5, 0.1M HCl).

EXAMPLE 7 9-(R)-(2-Hydroxypropyl)quanine

A suspension of 2-amino-6-chloropurine (18.6 g, 0.11 mol, Mack) andcesium carbonate (17.9 g, 0.055 mol) in dimethylformamide (350 ml) wasstirred at 100° C. under calcium chloride protection tube and a solutionof (R)-(2-O-tetrahydropyranyl-1-O-p-toluenesulfonylpropane-1,2-diol (42g, 0.134 mol) in dimethylformamide (100 ml) was added dropwise over 30min. interval. The mixture was stirred at 100° C. for additional 6hours, cooled and evaporated at 50° C./13 Pa. The residue was extractedwith boiling chloroform (three 300-ml-portions) and the extractconcentrated in vacuo. This material was applied onto a column of silicagel (500 ml) in chloroform and eluted by the same solvent. The relevantUV-absorbing fractions were pooled, evaporated and dried in vacuo.9-(R)-(2-tetrahydropyranyloxypropyl)-2-amino-6-chloropurine was obtainedas yellow amorphous foam, R_(F) 0.64 (TLC in chloroform-methanol, 95:5)(10.7 g, 0.034 mol, 31%). For C₁₃H₁₈ClN₅O₂ (311.8) calc.: C, 50.08; H,5.82; Cl, 11.37; N, 22.47. found C, 49.92; H, 6.08; Cl, 11.44; N, 22.54.¹H-NMR spectrum (200 MHz, d6-DMSO): H-8: S, 1H, 8.06; 1′-CH₂: dd, 1H,4.01 (J_(1′,2′)=7.3, J_(gem)=14.2) and dd, 1H, 3.94 (J_(1″,2′)=5.4,J_(gem)=14.2); 2′-CH: m, 1H, 3.42; 3′-CH₃: d, 3H, 1.06 (J_(3′,2′)=5.4);tetrahydropyranyl: 1″-CH: dd, 1H, 5.07 (J=2.9, 8.3); 5″-CH₂: m, 4.02 anddt, 1H, 3.80 (J=2.0, 2.0, 11.7); other CH₂: m, 1.30-1.90.

A solution of9-(R)-(2-tetrahydropyranyloxypropyl)-2-amino-6-chloropurine (10 g, 0.032mol) in 1M hydrochloric acid (200 ml) was refluxed under stirring for 1hour, cooled, alkalized with ammonia and evaporated in vacuo. Theresidue was crystallized from boiling water (decolorized with activecharcoal) to afford 9-(R)-(2-hydroxypropyl)guanine (6.0 g, 0.029 mol,91%), m.p.255° C. For C₈H₁₁N₅O₂ (209.2) calc. C, 45.92; H, 5.30; N,33.48. found C, 46.02; H, 5.25; N, 33.41. ¹H-MNR spectrum (200 MHz,d₆-DMSO): NH: br, 1H, 10.80; H-8: s, 1H, 7.61; NH₂: br s, 2H, 6.74; OH:br, 1H, 5.05; 1′-CH₂: dd, 1H, 3.89 (J_(1′,2′)=3.7, J_(gem)=13.4) and dd,1H, 3.78 (J_(1″,2′)=7.8, J_(gem)=13.4); 3′-CH₃: d, 3H, 1.03(J_(3′,2′)=6.1) [α]_(D)=−35.7° (c=0.5, 0.1M HCl).

EXAMPLE 8 9-(s)-(2-Hydroxypropyl)quanine

To a slurry of 4 g (0.1 mol) of 60% NaH dispersion in mineraloil(Janssen) in distilled dimethylformamide (300 ml) in a 1l-round-bottom flask equipped with calcium chloride protecting tube wasadded in one portion 2-amino-6-chloropurine (17.5 g, 0.1 mol,Mack) andthe mixture was magnetically stirred for 1 hour at ambient temperature.(S)-(2-O-Tetrahydropyrany-1-O-p-toluenesulfonylpropane-1,2-diol (34.5 g,0.11 mol) was then added in one portion and the mixture stirred at 60°C. for 3 hours and at 80° C. for 8 hours. The solvent was then removedat 50° C./13 Pa and the residue triturated with boiling chloroform (two300 ml portions) and filtered. The filtrate was chromatographed on asilica gel column (300 ml) to give9-(S)-(2-O-tetrahydropyranyloxypropyl)-2-amino-6-chloropurine (10.9 g,0.035 mol, 35%) as an amorphous foam. This material was refluxed in amixture of 2M hydrochloric acid (100 ml) and dioxane (100 ml) for 1hour, cooled, neutralized with aqueous ammonia and evaporated in vacuo.The residue afforded by crystallization from water (decolorized withactive charcoal) 9-(S)-(2-hydroxypropyl)guanine (5.7 g, 0.027 mol, 77%),m.p.256° C. For C₈H₁₁.N₅O₂ (209.2) calc. C, 45.92; H, 5.30; N, 33.48.found C, 45.88; H, 5.25; N, 33.41. ¹H-NMR spectrum (200 MHz, d₆-DMSO)was identical with that of the (R)-isomer. [α]_(D)=+36.2° (c=0.5, 0.1MHCl).

EXAMPLE 9 1-(R)-(2-Hydroxypropyl)cytosine

A mixture of cytosine (8.5 g, 76 mmol, Fluka), cesium carbonate (13 g,40 mmol) and(R)-2-O-tetrahydropyrany-1-O-p-toluenesulfonylpropane-1,2-diol (24 g,76mmol) in distilled dimethylformamide (300 ml) was stirred at 100° C. for12 hours and filtered while hot. The filtrate was stripped off thesolvent in high vacuum and the residue triturated with boilingchloroform (three 200-ml-portions) and filtered. The filtrate affordedby chromatography on a silica gel column to give1-(R)-(2-tetrahydropyranyloxypropyl)cytosine (4.6 g, 18 mmol, 23.5%),m.p.259-260° C. (crystallized from ethyl acetate-petroleum ethermixture). For C₁₂H₁₉N₃O₃ (MW 253,3) calculated: C,56.89; H, 7.57; N,16.59. found: C, 55.80; H, 7.72; N, 16.85. ¹H-NMR (200 MHz, d₆-DMSO)(mixture of diastereomers, 3:1), major isomer: H-5: d, 1H, 5.73(J_(5,6)=7.3), H-6: d, 1H, 7.52 (J_(5,6)=7.3); d, 3H, 1.13 (J=6.1), NH2:br s, 2H, 6.98; tetrahydropyranyl C-1″: br t, 1H, 4.36 (J=3.2); otherCH₂ groups : m, total 10H, 1.20-1.70, 3.26-3.54, 3.72-4-01.

A solution of 1-(R)-(2-tetrahydropyranyloxypropyl)cytosine (4.0 g, 16mmol) in 0.25 M sulfuric acid (50 ml) was left to stand at ambienttemperature overnight and neutralized with saturated aqueous bariumhydroxide solution to pH 7.0-7.1. The suspension was warmed to 80° C.,filtered through a layer of Celite 521 (Janssen) and the filter washedwith boiling water (500 ml). The filtrate was taken down to dryness invacuo and the residue codistilled with ethanol (200 ml). The residue wascrystallized from ethanol (ether added to turbidity) to give1-(R)-(2-hydroxypropyl)cytosine (2.5 g, 15 mmol, 94%), m.p.246° C. ForC₇H₁₁N₃O₂ (169,2) calculated: C, 49.69; H, 6.55; N, 24.84. found: C,49.48; H, 6.70; N, 24.70. ¹H-NHR-Spectrum (500 MHz, d6-DMSO): H-5: d,1H, 5.61 (J_(5,6)=7.3); H-6: d, 1H, 7,45 (J_(5,6) =7.3); NH2: 2×br s,2×1H, 7.04 and 6.98; OH: br, 1H, 4.88; 1′-CH₂: dd, 1H, 3.73(J_(1′,2′)=3.9, J_(gem)=13.2) and dd, 1H, 3.31 (J_(1″,2′)=8.05,J_(gem)=13.2); 2′-CH: m, 1H, 3.82 (J=31.0); 3′-CH₃: d, 3H, 1.08(J_(3′,2′)=6.35). [α]_(D)=−107.0° (c=0.5, 0.1M HCl).

EXAMPLE 10 1-(R)-(2-Hydroxypropyl)cytosine

To a slurry of sodium hydride (4 g, 0.1 mol, 60% suspension) indistilled dimethylformamide (300 ml) was added under stirring4-methoxy-2-pyrimidone (12.6 g, 0.1 mol) and the mixture stirred for 1hour under exclusion of moisture (calcium chloride protection tube). Theresulting clear solution was treated with(R)-2-O-tetrahydropyrany-1-O-p-toluenesulfonylpropane-1,2-diol (31.4 g,0.1 mol) and the reaction mixture heated at 80° C. for 8 hours understirring. The solvent was then removed in vacuo and the residuetriturated with boiling chloroform (three 200-ml-portions) and filtered.The filtrate was purified by silica chromatography to afford1-(R)-(2-O-tetrahydropyranyloxypropyl)-4-methoxy-2-pyrimidone (16.9 g,63 mmol, 63%) as an amorphous foam.

This product was heated with methanolic ammonia (500 ml, saturated at 0°C.) in a steel autoclave at 110° C. for 8 hours, cooled and thesuspension evaporated in vacuo. The residue was dissolved in 0.25 Msulfuric (300 ml) acid and the solution warmed at 70° C. for 5 hours.The mixture was neutralized with aqueous ammonia, filtered through alayer of Celite 521 (Janssen) and the filtrate concentrated in vacuo.The resulting solution was applied onto a column of Dowex 50×8 (250 ml,100-200 mesh) in acid form and the column was eluted with water to theloss of UV-absorption of the eluate. The subsequent elution with diluted(1:10) aqueous ammonia afforded UV-absorbing fraction which was pooledand evaporated in vacuo. Crystallization from ethanol gave1-(R)-(2-hydroxypropyl)cytosine (7.8 g, 46 mmol, 73%), identical withthe product prepared according to Example 9.

EXAMPLE 11 9-(R)-(2-Hydroxypropyl-N⁶-benzoyladenine

A suspension of 9-(R)-(2-hydroxypropyl)adenine (5.8 g, 30 mmol) inpyridine (160 ml) was treated with chlorotrimethylsilane (26 ml) and themixture was stirred for one hour. Benzoyl chloride (20 ml) was thenadded and the mixture stirred for additional 2 hours. The reactionmixture was placed in ice-water bath and ice-cold water (30 ml) andconcentrated aqueous ammonia (70 ml) were subsequently added dropwiseunder stirring over 15 min. The mixture was evaporated in vacuo. Theresidue was codistilled with ethanol (three 150-ml-portions) andcrystallized from boiling water. The crystalline product was collectedand recrystallized from ethanol (ether added to turbidity) to afford9-(R)-(2-hydroxypropyl)-N⁶-benzoyladenine (7.8 g, 26 mmol, 87%),m.p.227° C. R_(F) 0.40 (TLC, chloroform-methanol, 4:1). For C₁₅H₁₅N₅O₂(297.3) calc.:C, 60.59; H, 5.09; N, 23.56. found C, 60.73; H, 5.28; N,23.47. ¹H-NMR-Spectrum (200 MHz, d₆-DMSO): H2,H8: 2×s, 2×1H, 8.73 and8.42, N—CH₂+O—CH: m, 3H, 4.05-4.30; 3-CH₃: d, 3H, 1.11 (J=5.6); arom.protons+NH: m, 6H, 7.30-8.10. [α]_(D)=+21.7° (c=0.5, DMF).

EXAMPLE 12 9-(S)-(2-Hydroxypropyl)-N6-benzoyladenine

To a stirred suspension of 9-(S)-(2-hydroxypropyl)adenine (6.8 g, 35mmol) in pyridine (160 ml) was added chlorotrimethylsilane (26 ml) andthe mixture was stirred for 1 hour. Benzoyl chloride (20 ml) was addedin one portion, the mixture was stirred for additional 2 hours andcooled in ice-water bath. Ice-cold water (30 ml) and conc. aqueousammonia (70 ml) were added over 15 minute interval and the mixturestirred for additional 30minutes at 0° C. The solvents were evaporatedin vacuo and the residue codistilled with water. After crystallizationfrom water the product was collected and recrystallized from ethanol toafford 9-(S)-(2-hydroxypropyl)-N⁶-benzoyladenine (4.4 g, 15 mmol, 43%),m.p.230° C. The combined mother liquors were evaporated in vacuo and theresidue stirred with ethanol (150 ml) for 30 minutes. The suspension wasfiltered and the precipitate of inorganic salts washed with ethanol (50ml) and discarded. The filtrate was taken down to dryness in vacuo andthe residue triturated with chloroform (two 150-ml-portions) andfiltered. The filtrate was chromatographed on a silica gel column (200ml) to afford, after crystallization from ethyl acetate (petroleum etheradded to turbidity) additional crop of the product. Total yield, 7.4 g(25 mmol, 71.5%). For C₁₅H₁₅N₅O₂ (297.3) calc.:C, 60.59; H, 5.09; N,23.56. found C, 60.63; H, 5.16; N, 23.30. ¹H-NMR spectrum was identicalwith that of the (R)-isomer in Example 11. [α]_(D)=−25.2° (c=0.5, 0.1MHCl).

EXAMPLE 13 9-(S)-(2-Hydroxypropyl)-N²-benzoylguanine

Chlorotrimethylsilane (20 ml) was added in one portion to a stirredsuspension of 9-(R)-(2-hydroxypropyl)guanine (5.0 g, 24 mmol) inpyridine (130 ml) and, after 1 hour stirring, benzoyl chloride (16 ml)was added in one portion. The mixture was stirred for additional 2hours, cooled by ice-water bath and ice-water (24 ml) followed by conc.aqueous ammonia (56 ml) were added dropwise over 10 minute interval. Thereaction mixture was stirred for additional 30 minutes and evaporated invacuo. The residue was triturated with mixture of water (200 ml) andethyl acetate (200 ml), filtered, washed with water, ether and dried invacuo. 9-(S)-(2-Hydroxypropyl)-N²-benzoylguanine (3.4 g, 11 mmol, 45%)obtained was chromatographically pure: R_(F) 0.33 (TLC,chloroform-methanol, 4:1). m.p.278° C. For C₁₅H₁₅N₅O₃.2H₂O (349.4)calc.:C, 51.56; H, 5.49; N, 20.05. found C, 51.48; H, 5.41; N, 20.05.¹H-NMR Spectrum (500 MHz, d₆-DMSO): NH: 2×br, 2×1H, 12.30 and 11.90; H8:s, 1H, 7.95; OH: d, 1H, 5.05 (J_(2′,OH)=4.9); 1′-CH₂: dd, 1H, 4.05(J_(1′,2′)==3.4,J_(gem)=12.5) and dd, 1H, 3.96(J_(1″,2′)=7.1,J_(gem)=12.5), 2′-CH: br m, 1H, 4.01; 3′-CH₃: dd, 3H,1.09 (J_(3′,2′)=6.1); arom.protons: m, 2H, 8.05 and m, 3H, 7.50-7.70.[α]_(D)=+28.1° (c=0.5, DMF).

EXAMPLE 14 9-(R)-(2-Hydroxypropyl)-N2-benzoylguanine

The reaction mixture composed of 9-(R)-(2-hydroxypropyl)guanine (2.5 g,12 mmol), pyridine (65 ml) and chlorotrimethylsilane (10 ml) was stirredin a stoppered flask for 1 hour at ambient temperature and benzoylchloride (8 ml) was added in one portion. After additional 2 hoursstirring the mixture was cooled by ice and ice-water (12 ml) followed byconc. aqueous ammonia (28 ml) were added over 5 minute period. After 30minutes at 0° C., the solvents were evaporated in vacuo and the residuecodistilled with ethanol. Crystallization from 80% aqueous ethanolafforded 9-(R)-(2-hydroxypropyl)-N2-benzoylguanine (2.4 g, 7.6 mmol,63.5%), m.p. 276° C. For C₁₅H₁₅N₅O₃.2H₂O (349.4) calc.:C, 51.56; H,5.49; N, 20.05. found C, 51.28; H, 5.62; N, 20.24. ¹H-NMR spectrum wasidentical with that of the (S)-isomer (Example 13). R_(F) 0.33 (TLC,chloroform-methanol, 4:1). [α]_(D)=−28.4° (c=0.5, DMF).

II. Synthesis of Intermediates of the Formula XVII EXAMPLE 15(S)-2-(Di(2-propyl)phosphonylmethoxy)-1-(p-toluenesulfonyloxy)propane

To a suspension of sodium hydride (17.2 g, 60% dispersion in oil, 0.43mol) in dimethylformamide (400 ml) placed in a 1 l round-bottom flaskwith dropping funnel and calcium chloride protecting tube was understirring and cooling with ice added dropwise over 30 minutes(S)-2-O-tetrahydropyrany-1,2-propanediol (69.2 g, 0.43 mol). Thesuspension was stirred for additional 1 hour at 0° C. and benzyl bromide(51 ml, 0.43 mol) was added dropwise at 0° C. The mixture was stirredfor 4 hours at 0° C. and left to stand for 48 hours at ambienttemperature. Methanolic ammonia (30% solution, 20 ml) was added and,after standing for 2 hours, the solvent was taken down in vacuo. Ethylacetate (500 ml) was added and the mixture washed with water (four100-ml-portions). The organic phase was evaporated and the resulting oilin 70% aqueous methanol (400 ml) was stirred under reflex with 50 mlDowex 50×8 (acid form) for 4 hours. The warm mixture was filtered,washed with methanol and the filtrate evaporated in vacuo. The residualoil was taken in ether (200 ml), washed with water (50 ml), dried anddistilled in vacuo. Yield, 60.8 g (85%, b.p. 100-105° C./20 Pa)(S)-1-O-benzyl-1,2-propanediol, [α]_(D)=−13.6° (c=0.5, CHCl₃).

This material (0.37 mol) in 1,2-dichlorethane (200 ml) was stirred withparaformaldehyde (20 g) and calcium chloride (10 g) under simultaneousintroduction of dry hydrogen chloride for 2 hours at 0° C. The mixturewas taken down in vacuo, the residue codistilled with toluene (three50-ml-portions) and tri(2-propyl)phosphite (50 g) was added. The mixturewas heated under stirring to 110° C. and the evolved volatile materialdistilled off. After the exothermic reaction has subsided, the mixturewas heated up to 150° C. and finally the volatiles distilled off at 140°C./1 kPa. The resulting material was filtered through a column (200 ml)of alumina, elution with benzene (0.5 1). The eluate was evaporated andthe residue distilled in vacuo to yield(S)-1-benzyloxy-2-[di(2-propyl)phosphonylmethoxy]propane (44 g, 35%,b.p. 125-130° C./13 Pa. For C17H29O5P (344.4) calc.: C,59,28;H,8,49;P,9,01. found C, 59.44; H, 8.28; P, 9.30. Mass-spectrum: Mol.peak345.1 (M+1).

This product (44 g, 0.128 mol) in methanol (400 ml) was hydrogenatedovernight with 10% palladium-on-charcoal (1.5 g, Merck) and conc.hydrochloric acid (0.7 mol) at atmospheric pressure. The mixture wasfiltered, the filtrate alkalized by the addition of triethylamine andevaporated in vacuo. The residue in ether (200 ml) was washed with water(two 20-ml-portions), dried over magnesium sulfate and evaporated invacuo to afford (S)-2-(di(2-propyl)phosphonylmethyl)propane-1,2-diol(24.4 g, 75%) as colorless oil.

This residue (24.4 g, 96 mmol) and 4-dimethylaminopyridine (1 g) inpyridine (200 ml) were treated dropwise at 0° C. under stirring with asolution of tosyl chloride (22 g, 0.115 mol) in pyridine (100 ml) andthe mixture left to stand at 0° C. overnight. Water (10 ml) was added anthe solvent evaporated in vacuo to about half of the original volume.Ethyl acetate (300 ml) was added, the mixture washed successively (100ml portions) with water, 1M Hcl (to acidic reaction), water, saturatedsodium hydrogen carbonate and water. The solution was finally dried withmagnesium sulfate and evaporated in vacuo to afford crude product whichwas purified by chromatography on a column of silica gel (elution bychloroform).(S)-2-[Di(2-propyl)phosphonylmethoxy]-1-p-toluenesulfonyloxypropane wasobtained as a thick yellowish oil which was used for furtherpreparations (28 g, 69 mmol).

EXAMPLE 16(R)-2-[di(2-propyl)phosphonylmethoxy]-1-p-toluenesulfonyloxypropane

The synthesis was performed essentially as described in Example 15starting with (R)-2-O-tetrahydropyrany-1,2-propanediol (42 g, 0.262mol). 1-O-Benzyl-(R)-propane-1,2-diol was obtained by distillation invacuo (33 g, 76%, b.p. 98-102° C./Pa). [α]_(D)=−12.2° (c=0.5, CHCl₃).The chloromethylation and reaction with tri(2-propyl)phosphite gavecrude phosphoric acid diester (32 g) which was hydrogenated in methanol(300 ml) with 10% palladium-on-charcoal catalyst (1 g) and hydrochloricacid (0.5 ml) overnight. After work-up according to Example 15 theintermediate afforded(R)-2-[di(2-propyl)phosphonylmethoxy]-1-p-toluenesulfonyloxypropane (24g, 59 mmol).

III. Synthesis of Products of the Formula I EXAMPLE 179-(R)-(2-Phosphonomethoxypropyl)adenine

A mixture of 9-(R)-(2-hydroxypropyl)-N⁶-benzoyladenine (3 g, 10 mmol)and di(2-propyl)p-toluenesulfonyloxymethylphosphonate (4.2 g, 12 mmol)was codistilled with dimethylformamide (two 25-ml portions) at 40° C./13Pa. The residue was redissolved in dimethylformamide (50 ml), cooled byice and sodium hydride (1.2 g, 30 mmol, 60% dispersion in oil) was addedin one portion. The resulting mixture was stirred under calcium chlorideprotecting tube at ambient temperature for 48 hours. 0.1 M sodiummethoxide solution in methanol (150 ml) was added and the mixture setaside overnight under exclusion of moisture. Dowex 50×8 (acid form) wasthen added to acid reaction of the mixture followed by triethylamine toalkaline reaction of the suspension. After filtration and washing theresin with methanol (200 ml) the filtrate was evaporated to dryness(finally at 40° C./13 Pa). The residue in water (200 ml)was extractedwith ether (two 100 ml portions) and the aqueous phase concentrated invacuo (to approx. 100 ml). This solution was applied onto a Dowex 50×8column (250 ml) and washed with 20% aqueous methanol until theUV-absorption of the eluate dropped to the original level. The productwas then eluted with diluted (1:10) ammonia, pertinent UV-absorbingfractions were pooled and evaporated in vacuo. The residue wascodistilled with ethanol (two 50 ml portions) and dried at 13 Pa overphosphorus pentoxide overnight to afford crude di(2-propyl)ester (3 g),R_(F) =0.55 (TLC chloroform-methanol, 4:1).

Acetonitrile (50 ml) and bromotrimethylsilane (5 ml) were added to thisresidue and the suspension dissolved by stirring. After standingovernight at ambient temperature in a stoppered flask, the mixture wasevaporated in vacuo and water (100 ml) was added to the residue. Themixture was alkified by aqueous ammonia and evaporated in vacuo. Theresidue dissolved in water was applied on a column of Dowex 50×8 (250ml, acid form) which was washed with water to the drop of UV-absorptionof the eluate followed by elution with aqueous ammonia (1:10) solution.The product containing fraction was evaporated to dryness in vacuo andthe residue redissolved in water (50 ml) by alkalization with conc.ammonia to pH 9-9.5. This solution was applied on a column of Dowex 1×2(250 ml, acetate form) which was then washed with 0.02 M acetic acid tothe drop of the UV-absorption of the eluate. The elution was thencontinued by linear increase of acetic acid concentration (0.02M-1M over2 liters); the product eluted at 1 M acetic acid. The relevant fractionswere pooled, evaporated in vacuo and the residue codistilled with water(three 50-ml-portions). Crystallization from boiling water (threevolumes of ethanol added after dissolution) afforded9-(R)-(2-phosphonomethoxypropyl)adenine (1.35 g, 4.7 mmol, 47%), m.p.279°. For C₉H₁₄N₅O₄P.H₂O (305.3) calc.:C, 35.40; H, 5.29; N, 22.94; p,10.17. found C, 35.28; H, 5.37; N, 23.03; P, 10.17. Electrophoreticmobility (referred to uridine 3′-phosphate): E_(Up)=0.80 (in 0.05 Mtriethylammonium hydrogen carbonate, pH 7.5; 20V/cm). ¹H-NMR spectrum(200 Mhz, D₂O+NaOD): H2: s, 1H, 8.25; H8: s, 1H, 8.09; 1′-CH₂: dd, 1H,4.35 (J_(1′,2′)=4.4; J_(gem)=14.4) and dd, 1H, 4.22 (J_(1″,2′)=5.1,J_(gem)=14.4); 2′-CH: m, 1H, 3.97 (J=28.4); 3′-CH₃: d,3H, 1.11(J_(3′,2′)=6.3); P—CH₂: dd, 1H, 3.57 (J_(p,CH)=9.5,J_(gem)=12.4) and dd,1H, 3.46 (J_(P,CH)=9.3,J_(gem)=12.4). [α]_(D)=+21.2° (c=0.5, 0.1M HCl).

EXAMPLE 18 9-(S)-(2-Phosphonomethoxypropyl)adenine

A solution of 9-(S)-(2-hydroxypropyl)-N⁶-benzoyladenine (3.57 g, 12mmol) and di(2-propyl)p-toluenesulfonyloxymethylphosphonate (5.25 g, 15mmol) in dimethylformamide (50 ml) was cooled to −20° C. and sodiumhydride (1.44 g, 36 mmol) as 60% dispersion on oil was added in oneportion. The mixture was stirred at 0° C. for 3 hours and 48 hours atroom temperature under protection against moisture. Further work-up ofthe reaction mixture was performed as described in Example 17. Afterpurification by chromatography on the column of Dowex 1×2 the productwas crystallized from water-ethanol to give9-(S)-(2-phosphonomethoxypropyl)adenine (1.9 g, 6.7 mmol, 56%). M.p.276-278° C. For C₉H₁₄N₅O₄P.H₂O (305.3) calc.:C, 35.40; H, 5.29; N,22.94; p, 10.17. found C, 35.33; H, 5.56; N, 23.14; P, 10.00.Electrophoretic mobility and ¹H-NMR spectrum are identical with those ofthe (R)-isomer (Example 17). [α]_(D)=−21.2° (c=0.5, 0.1M HCl).

EXAMPLE 19 9-(R)-2-Phosphonomethoxypropyl)-2,6-diaminopurine

9-(R)-(2-Hydroxypropyl)-2,6-diaminopurine (2.1 g,10 mmol) was dissolvedby warming in a mixture of dimethylformamide (40 ml) anddimethylformamide dimethylacetal (25 ml) and the solution was left tostand aside in a stoppered flask overnight. The mixture was evaporatedat 40° C./13 Pa and codistilled with dimethylformamide (two20-ml-portions). 50% aqueous pyridine (50 ml) was added to the residuefollowed up by dry ice, the mixture was evaporated at 40° C./13 Pa,codistilled with pyridine (four 25-ml-portions) anddi(2-propyl)p-toluenesulfonyloxymethylphosphonate (4.2 g, 12 mmol) wasadded to the residue. The mixture was then codistilled withdimethylformamide (two 25-ml-portions), redissolved in the same solvent(40 ml) and cooled down to −10° C. Sodium hydride (1.2 g, 30 mmol) as60% suspension in oil was added in one portion and the mixture stirredat 0° C. for 3 hours and 48 hours at room temperature under protectionagainst moisture. Acetic acid (1.8 ml, 30 mmol) was added, the mixturewas evaporated at 40° C./13 Pa to dryness. The residue was dissolved indiluted (1:1) aqueous ammonia, (100 ml), left to stand overnight andevaporated to dryness in vacuo. The residue was deionized on the columnof Dowex 50×8 (200 ml) as described in Example 15 and the ammonia eluatedried at 13 Pa over phosphorus pentoxide overnight.

Acetonitrile (30 ml) and bromotrimethylsilane (3 ml) were added and themixture homogenized by gentle shaking in a stoppered flask. The solutionwas left to stand overnight and evaporated in vacuo. The residue wasdissolved in water (100 ml) and, after 30 minutes standing the solutionwas alkalified by ammonia and evaporated. This residue was deionized ona Dowex 50×8 column (200 ml, acid form) as described in Example 17. Theresidue of ammonium salt was dissolved in water (50 ml) by addition ofammonia to pH 9-9.5 and this solution was applied on a column (200 ml)of Sephadex A-25 in hydrogen carbonate form, equilibrated by 0.02 Mtriethylammonium hydrogen carbonate. The column was first eluted by theequilibration buffer to the drop of UV-absorption and then by lineargradient of triethylammonium hydrogen carbonate (pH 7.5) (formed from0.02 M and 0.3 M buffer, 1 l each). The product eluted at 0.10-0.15 Mconcentration, the relevant fractions were pooled, evaporated in vacuoand the residue coevaporated with methanol (three 50-ml-portions). Theresidue dissolved in water (25 ml) was applied on a column (50 ml) ofDowex 1×2 (acetate) which was first washed with water to thedisappearance of UV-absorption. The resin was transferred to a 300 mlbeaker and stirred with 1M acetic acid (200 ml). The suspension wasfiltered and the resin washed with boiling water (1 liter). The combinedfiltrate was evaporated in vacuo and the residue codistilled with water(three 50-ml-portions). The residue was dissolved in boiling water (100ml), filtered while hot and ethanol (150 ml) added to the filtrate. Theproduct which crystallized on ice-cooling was collected by filtration,washed with ethanol, ether and dried in vacuo.9-(R)-(2-Phosphonomethoxypropyl)-2,6-diaminopurine (1.4 g, 4.7 mmol,47%) was obtained as a free acid, m.p. 287° C. For C₉H₁₅N₆ O₄P.H2O(302.3) calc.:C, 35.75; H, 5.00; N, 27.80; P, 10.27. found C, 35.93; H,5.02; N, 27.59; P, 10.28. ¹H-NMR-Spectrum (500 MHz, D₂O+NaOD): H8: s,1H, 7.94: 1′-CH₂: dd, 1H, 4.7 (J_(1′,2′)=4.4) and dd, 1H, 4.09(J_(1″,2′)==5.4, J_(gem)=14.65); 2′-CH: m, 1H, 3.93 (J=28.8); 3′-CH₃: d,3H, 1.12 (J_(CH3,CH)=6.3); P—CH₂: dd, 1H, 3.54, (J_(P,CH)=9.3,J_(gem)=12.2) and dd, 1H, 3.45 (J_(P,CH)=9.3,J_(gem)=12.2):Electrophor.mobility:E_(Up)=0.70. [α]_(D)=−26.1° (c=0.5, 0.1M HCl).

EXAMPLE 20 9-(S)-(2-Phosphonomethoxypropyl)-2.6-diaminopurine

This compound was prepared from9-(S)-(2-hydroxypropyl)-2,6-diaminopurine (2.1 g, 10 mmol) essentiallyas described in Example 19 for its (R)-enantiomer. The yield of9-(S)-(2-phosphonomethoxypropyl)-2,6-diaminopurine crystallized as freeacid from water-ethanol amounted to 33% (1.0 g, 3.3 mmol). M.p. 275-278°C. For C₉H₁₅.N₆O₄P.H₂O (302.3) calc.:C, 35.75; H, 5.00; N, 27.80; P,10.27. found C, 35.56; H, 5.08; N, 27.99; P, 10.18. Electrophoreticmobility: E_(Up)=0.70; ¹H-NMR spectrum is identical with that of its(R)-enantiomer (Example 19). [α]_(D)=+28.5° (c=0.5, 0.1M HCl).

EXAMPLE 21 9-(R)-(2-Phosphonomethoxypropyl)quanine

A mixture of 9-(R)-(2-hydroxypropyl)-N²-benzoylguanine (2.5 g, 7 mmol)and di(2-propyl)p-toluenesulfonyloxymethylphosphonate (2.9 g, 8.4 mmol)was codistilled with dimethylformamide (two 25-ml-portions) at 40° C./13Pa and the residue redissolved in dimethylformamide (30 ml). Sodiumhydride (0.84 g, 21 mmol) in 60% dispersion in oil was added at oneportion and the mixture stirred for 24 hours at room temperature underthe exclusion of moisture. Methanol (100 ml) was added to the mixturewhich was then left to stand overnight, neutralized with Dowex 50×8(acid form) and filtered. The filtrate was evaporated to dryness in highvacuum and the residue in water (150 ml) extracted with ether (two50-ml-portions). The aqueous solution was concentrated in vacuo toapprox. 50 ml and applied on a column of Dowex 50×8 (150 ml) (acid form)which was first washed with water to the drop of UV-absorption and thenwith diluted (1:10) ammonia. The ammonia fraction was evaporated, theresidue codistilled with ethanol (two 50-ml-portions) and finally driedovernight at 13 Pa over phosphorus pentoxide.

Acetonitrile (40 ml) and bromotrimethylsilane (4 ml) were added to theresidue and the mixture dissolved by stirring in a stoppered flask.After standing overnight at ambient temperature, the mixture wasevaporated in vacuo and the residue dissolved in water (100 ml). After30 minutes, the solution was alkalized with ammonia and evaporated. Thedeionization and purification on Dowex 1×2 were performed essentially asdescribed in Example 17. The final purified free acid form of9-(R)-(2-phosphonomethoxypropyl)guanine was precipitated from ethanolwith ether to give 0.90 g (3 mmol, 43%) of the material with m.p. 286°C. For C₉H₁₄N₅O₅P (303.3) calc.:C, 35.64; H, 4.65; N, 23.10; P, 10.23.found C, 35.35; H, 4.58; N, 23.24; P, 10.40. [α]_(D)=−26.1° (c=0.5, 0.1MHCl). ¹H-NMR-Spectrum (500 MHz, D₂O, NaOD): H-8: s, 1H, 7.90; 1′-CH₂:dd, 1H, 4.21 (J_(1′,2′)=4.6, J_(gem)=14.5) and dd, 1H, 4.15(J_(1″,2′)=5.5, J_(gem)=14.5); 2′-CH: m, 1H, 3.99 (ΣJ=28.7); 3′-CH₃: d,3H, 1.14 (J_(3′,2′=)6.2); P—CH₂: dd, 1H, 3.56 (J_(P,CH)=9.3,J_(gem)=12.4) and dd, 1H, 3.48 (J_(P,CH)=9.2, J_(gem)=12.4).

EXAMPLE 22 9-(S)-(2-Phosphonomethoxypropyl)guanine

A mixture of 9-(S)-(2-hydroxypropyl)guanine (1.57 g, 5 mmol) anddi(2-propyl)p-toluenesulfonyloxymethylphosphonate (2.1 g, 6 mmol) wascodistilled with dimethylformamide (two 20-ml-portions) at 40° C./13 Paand the residue redissolved in dimethylformamide (20 ml). Sodium hydride(0.6 g, 15 mmol)) as 60% dispersion in oil was added in one portion andthe mixture stirred for three days at room temperature under exclusionof moisture. Methanol (30 ml) was added and the solution left to standovernight. After neutralization with Dowex 50×8 (acid form) andfiltration, the filtrate was evaporated to dryness in vacuo and theresidue deionized as described in Example 17. The ammonia eluate of thecrude diester was dried at 13 Pa over phosphorus pentoxide. Acetonitrile(30 ml) and bromotrimethylsilane (3 ml) were added and the mixturedissolved by stirring. After standing overnight at room temperature, thereaction mixture was worked up as described in Example 17.9-(S)-(2-Phosphonomethoxypropyl)guanine was isolated as a free acidsimilarly as described for its (R)-enantiomer (Example 21) in the 43%yield (0.65 g, 2.15 mmol). m.p. 287° C. For C₉H₁₄N₅O₅P (303.3) calc.:C,35.64; H, 4.65; N, 23.10; P, 10.23. found C, 35.72; H, 4.54; N, 23.06;P, 10.29. ¹H-NMR-Spectrum is identical with that of the (R)-enantiomer.[α]_(D)=+26.3° (c=0.5, 0.1M HCl).

EXAMPLE 23 1-(R)-(2-Phosphonomethoxypropyl)cytosine

The mixture of 1-(R)-(2-hydroxypropyl)cytosine (1.7 g, 10 mmol),dimethylformamide (40 ml) and dimethylformamide dimethylacetal (15 ml)was stirred overnight and evaporated at 40° C./13 Pa. 50% aqueouspyridine (20 ml) and enough dry ice was added to keep its excess for 15minutes. The mixture was again evaporated and codistilled with pyridine(three 25-ml-portions) at 40°/13 Pa.Di-(2-propyl)p-toluenesulfonyloxyphosphonate (4.2 g, 12 mmol) was addedand the mixture codistilled with dimethylformamide (two 25-ml-portions)under the same conditions. The residue in dimethylformamide (40 ml) wastreated at −10° C. with sodium hydride (720 mg, 30 mmol) and the mixturestirred at ambient temperature for 48 hours under exclusion of moisture.0.1 M Sodium methoxide in methanol (100 ml) was added and, afterstanding overnight, the mixture was neutralized with Dowex 50×8 (acidform). The suspension was filtered, evaporated to dryness in vacuo andthe residue deionized on a column of Dowex 50×8 (acid form, 150 ml). Theammonia eluate was evaporated, dried in vacuo over phosphorus pentoxideand the residue treated with bromotrimethylsilane (3 ml) andacetonitrile (30 ml) overnight. After evaporation in vacuo, the residuewas treated with water (50 ml), alkalized with ammonia and evaporated invacuo. The residue was deionized on a column of Dowex 50×8 (see above)and the crude material purified by anion exchange chromatography onDowex 1×2 (acetate) column (100 ml) with a linear gradient of aceticacid (composed of 1 l water and 1 l 0.3 M acetic acid). The productfraction was evaporated, codistilled with water (three 30-ml-portions)and 1-(R)-(2-phosphonomethoxypropyl)cytosine (0.90 g, 19%) obtained bycrystallization from water-ethanol. M.p. 261° C. E_(Up)=0.70. ForC₈H₁₄N₃O₅P (263.3) calc.: C, 36.50; H, 5.36; N, 15.97; P, 11.79. foundC, 36.43; H, 5.39; N, 16.05; P, 11.82. [α]_(D)=−108.10° (c=0.5, 0.1MHCl).

EXAMPLE 24 9-(S)-(2-Phosphonomethoxypropyl)adenine

A mixture of adenine (1.62 g, 12 mmol) and cesium carbonate (2.1 g, 6.5mmol) in dimethylformamide was stirred at 100° C. and a solution of(S)-2-[(di(2-propyl)phosphonylmethoxy]-1-toluenesulfonyloxypropane (4.1g, 10 mmol) in dimethylformamide (10 ml) was added in one portion. Themixture was heated at 110° C. under stirring with exclusion of moisturefor 8 hours and evaporated in vacuo. The residue was triturated withboiling chloroform (three 50-ml-portions), filtered and evaporated invacuo. The crude material afforded on purification by silica gelchromatography (150 ml) di-(2-propyl)(S)-9-(2-phosphonomethoxypropyl)adenine which crystallized from ether(1.7 g, 46%), m.p. 97-98° C. For C₁₅H₂₆N₅O₄P (371.5) calc.: C, 48.50; H,7.06; N, 18.86; P, 8.36. found C, 48.27; H, 7.15; N, 18.85; P, 8.44.[α]_(D)=+2.80 (c=0.5, DMF).

This product (1.4 g, 3.9 mmol) in acetonitrile (25 ml) was treated withbromotrimethylsilane (2.5 ml) overnight at room temperature. The mixturewas taken down in vacuo and the product desalted and purified bychromatography on Dowex 1×2 column (100 ml) as described in Example 17.Yield, 76%, m.p. 277-278° C. [α]_(D)=+21.7.

EXAMPLE 25 9-(R)-(2-Phosphonomethoxypropyl)adenine

The reaction was performed with 12 mmol adenine and 10 mmol(R)-2-[(di(2-propyl)phosphonylmethoxy]-1-toluenesulfonyloxypropaneaccording to Example 22. Di(2-propyl)(R)-9-(2-phosphonomethoxypropyl)adenine m.p. 97° C. was obtained bychromatography on silica gel and crystallized from ether (2.8 g, 75.5%).For C₁₅H₂₆N₅O₄P (371.5) calc.: C, 48.50; H, 7.06; N, 18.86; P, 8.36.found C, 48.78; H, 7.22; N, 18.77; P, 8.23. [α]_(D)=−2.9° (c=0.5, DMF).The reaction of this product (1.8 g, 4.9 mmol) with bromotrimethylsilane(3 ml) and acetonitrile (30 ml) was performed as described in Example22. Yield, 80% of 9-(R)-(2-phosphonomethoxypropyl)adenine.[α]_(D)=21.5°, m.p. 279° C.

EXAMPLE 26 9-(R)-(2-Phosphonomethoxypropyl)-2-aminopurine

Sodium hydride (1.4 g, 60% dispersion, 35 mmol) was added to a stirredsolution of 2-amino-6-chloropurine (5.94 g, 35 mmol) indimethylformamide (60 ml) and after 1 hour stirring at ambienttemperature(R)-2-[di(2-propyl)phosphonylmethoxy]-1-p-toluenesulfonyloxypropane(12.2 g, 30 mmol) in dimethylformamide (20 l ) was added in one portion.The mixture was stirred at 80° C. for 10 hours and evaporated in vacuo.The residue was extracted with boiling chloroform (300 ml), filtered andthe filtrate was evaporated in vacuo. The residue afforded by silica gelcolumn chromatography (elution with chloroform-methanol mixture, 95:5)di(2-propyl) 9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-chloropurine(7.5 g, 53%) as a thick oil, R_(F) 0.55 (TLC on silica gel inchloroform-methanol, 9:1).

A solution of this diester (2.5 g, 6.2 mmol) in 200 ml methanol and 0.5ml conc. hydrochloric acid was hydrogenated over 10% Pd/C catalyst (1 g)at room temperature overnight, the mixture was filtered, filtratealkalized with triethylamine and evaporated in vacuo. The residue wasdeionized on Dowex 50×8 (acid form) (100 ml) as described in Example 24and the ammonia eluate evaporated and dried in vacuo over phosphoruspentoxide. Acetonitrile (25 ml) and bromotrimethylsilane (2.5 ml) wasadded and the solution left to stand overnight at room temperature. Themixture was evaporated to dryness and the residue taken up in water (25ml). After 30 min the solution was alkalized with ammonia andevaporated. The residue afforded on deionization on Dowex 1×2 (acetate)(150 ml) with linear gradient of acetic acid (0.75 l water, 0.75 l 0.5 Macetic acid) product which was isolated from the pooled fractions bycrystallization from water-ethanol (1:1). Yield, 0.62 g (35.5%) of9-(R)-(2-phosphonomethoxypropyl)-2-aminopurine, m.p. 156° C. ForC₉H₁₄N₅O₄P (287.3) calc.: C, 37.62; H, 4.91; N, 24.38; P, 10.80. found:C, 37.42; H, 5.05; N, 24.65; P, 11.06.

EXAMPLE 27 9-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-thiopurine

A solution ofdi(2-propyl)-9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-chloropurine(2.5 g, 6.2 mmol) (prepared according to Example 26), thiourea (2.0 g)and absolute ethanol (100 ml) was stirred in reflux for one hour,alkalized with triethylamine and evaporated. The residue was extractedwith chloroform (2×100 ml), filtered and the filtrate taken down todryness and evaporated in vacuo. The residue (R_(F) 0.40, TLC on silicagel, chloroform-methanol, 4:1) was dried over phosphorus pentoxideovernight and treated with acetonitrile (30 ml) and bromotrimethylsilane(3 ml). After standing overnight at room temperature, the mixture wasevaporated to dryness and taken down in water (50 ml). After 30 min itwas alkalized with ammonia, evaporated in vacuo and the residuedeionized on Dowex 50 (cf. Example 25). The ammonia eluate was takendown in vacuo and applied on a column of Dowex 1×2 (acetate) (150 ml)which was washed first with water and with 1 M acetic acid (500 mleach). These eluates were discarded, the resin was stirred with 2 Mformic acid (500 ml), filtered and washed with boiling water (total, 1l). The filtrate was evaporated to dryness, the residue codistilled withwater (3×50 ml) and crystallized from water (equal volume of ethanoladded after dissolution). Yield, 1.0 g (50%)9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-thiopurine, m.p. 188° C.(dec.). For C₉H₁₄N₅O₄P (319.3) calc.: C, 33.85; H, 4.42; N, 21.94; P,9.72; S, 10.04. found: C, 33.83; H, 4.69; N, 22.15; P, 9.99; S, 10.30.

EXAMPLE 28 9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-azidopurine

A solution of di(2)-propyl)9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-chloropurine (2.5 g, 6.2mmol) (prepared according to Example 26) and lithium azide (1.0 g) indimethylformamide (40 ml) was stirred 4 hours at 100° C. under exclusionof moisture, filtered over Celite, washed with dimethylformamide (20 ml)and the filtrate evaporated in vacuo. The residue (R_(F) 0.30, TLC onsilica gel, chloroform-methanol, 9:1) was dried over phosphoruspentoxide overnight and treated with acetonitrile (20 ml) andbromotrimethylsilane (2 ml). After standing overnight at roomtemperature, the mixture was evaporated to dryness and taken down inwater (50 ml) After 30 min it was alkalized with ammonia, evaporated invacuo and the residue applied on Dowex 50 (acid form) column (100 ml).Washing with water eluted with retention the UV-absorbing peak of theproduct which was evaporated in vacuo and the residue crystallized fromwater (equal volume of ethanol added after dissolution. Yield, 0.95 g(47%) 9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-azidopurine, notmelting to 300° C. For C₉H₁₃N₈O₄P (328.3) calc.: C, 32.92; H, 3.99; N,34.14; P, 9.45. found: C, 233.03; H, 4.29; N, 33.75; P, 9.59.

EXAMPLE 29 9-(R)-(2-Phosphonomethoxypropyl)-2,6-diaminopurine

9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-azidopurine (0.30 g, preparedaccording to Example 27) in 50% aqueous methanol (200 ml) containinghydrochloric acid (0.5 ml) was hydrogenated over 10% Pd/C (0.5 g)overnight at room temperature. The mixture was filtered, washed withwater, filtrate alkalized with ammonia and evaporated in vacuo. Theresidue was deionized on a column of Dowex 50×8 (50 ml) (cf. Example 25)and the ammonia eluate evaporated to dryness. The residue in water (pHadjusted to 9) was applied on a column of Dowex 1×2 (acetate) which wasfirst washed with water to remove salts and the product was then elutedwith 1 M acetic acid. The fractions containing product were pooled,evaporated to dryness and codistilled with water (3×20 ml). The residuewas crystallized from water (ethanol added to turbidity) to afford9-(R)-(2-phosphonomethoxypropyl)-2,6-diaminopurine (120 mg) identicalwith the preparation according to Example 19.

EXAMPLE 30 9-(R)-(2-Phosphonomethoxypropyl)-3-deazaadenine

A mixture of 3-deazaadenine (1.45 g, 10.8 mmol), cesium carbonate (1.75g, 5.4 mmol) and dimethylformamide (25 ml) was stirred at 100° C. for 1h and a solution of(R)-2-[di(2-propyl)phosphonylmethoxy]-1-p-toluenesulfonyloxypropane(3.67 g, 9 mmol) in dimethylformamide (10 ml) was added in one portion.The mixture was then heated for 24 hours at 110° C. under exclusion ofmoisture and taken down to dryness. The residue was extracted withboiling chloroform (total 300 ml), filtered and the filtrate evaporated.The residue was chromatographed on a column of silica gel (300 ml) inchloroform affording, after crystallization of the relevant fractionsfrom ethyl acetate-petroleum ether, di(2-propyl)9-(R)-(2-phosphonomethoxypropyl)-3-deazaadenine in the yield of 1.07 g(32.2%), m.p. 122° C. For C₁₆H₂₇N₄O₄P (370.5) calc.: C, 51.87; H, 7.35;N, 15.13; P, 8.38. found: C, 52.03; H, 7.69; N, 15.15, P, 8.59.UV-Spectrum (pH2): 1_(max) 262 (ε16500).

This diester (1.0 g, 2.7 mmol) was treated with acetonitrile (25 ml) andbromotrimethylsilane (2.5 ml) overnight. The mixture was then worked upas described in Example 27 to afford, after deionization andchromatography on Dowex 1×29-(R)-(2-phosphonomethoxypropyl)-3-deazaadenine in 78% yield, notmelting to 300° C. For C₁₀H₁₅N₄O₄P (286.3) calc.: C, 41.95; H, 5.28; N,19.57; P, 10.84. found: C, 42.03; H, 5.63; N, 19.75; N, 19.75; P, 11.09.UV-Spectrum (pH2): 1_(max) 262 (ε16500). E_(Up)=0.68 (pH 7.5).

EXAMPLE 31 9-(R)-(2-Phosphonomethoxypropyl)-8-azaadenine and8-(R)-(2-phosphonomethoxypropyl)-8-azaadenine

A mixture of 8-azaadenine (1.45 g, 10.8 mmol), cesium carbonate (1.75 g,5.4 mmol) and dimethylformamide (25 ml) was preheated to 100° C. and asolution of (R)-2-[di(2-propyl)phosphonylmethoxy]-1-p-toluenesulfonyloxypropane (3.67 g, 9 mmol) in dimethylformamide (10 ml) was added in oneportion. The mixture was then heated for 6 hours at 110° C. underexclusion of moisture and taken down to dryness. The residue wasextracted with boiling chloroform (total 300 ml), filtered and thefiltrate evaporated. The residue was chromatographed on a column ofsilica gel (300 ml). Elution with chloroform containing 5% methanolafforded di(2-propyl) 9-(R)-(2-phosphonomethoxypropyl)-8-azaadenine as athick oil in yield of 0.90 g (37%). UV-Spectrum (pH2): 1_(max) 265.5(ε14000). R_(F) 0.50 (TLC on silica gel in chloroform-methanol, 9:1).Further elution with the same solvent afforded di(2-propyl)8-(R)-2-phosphonomethoxypropyl)-8-azaadenine as semisolid material inthe yield of 0.75 g (22%). UV-Spectrum (pH2): 1_(max) 284 nm. R_(F) 0.40(TLC on silica gel in chloroform-methanol 9:1).

Each fraction was separately treated with acetonitrile (25 ml) andbromotrimethylsilane (2.5 ml) overnight and the mixtures worked up asdescribed in Example 27. Chromatography on Dowex 1×2 column (50 ml)afforded 9-(R)-(2-phosphonomethoxypropyl)-8-azaadenine on elution with 2M acetic acid. Yield (after crystallization from water-ethanol, 79%.UV-Spectrum (pH2): 1_(max) 265 nm (ε14000). For C₈H₁₄N₆O₄P (289.3)calc.: C, 33.21; H, 4.88; N, 29.06; P, 10.73. found C, 32.97; H, 4.63;N, 29.00; P, 11.10.

8-(R)-(2-phosphonomethoxypropyl)-8-azaadenine was obtained similarly byelution with 1 M acetic acid. Yield, 72%. UV-Spectrum (pH2): 1_(max) 284nm. For C₈H₁₄N₄O₄P (289.3) calc.: C, 33.21; H, 4.88; N, 29.06; P, 10.73.found: C, 33.45; H, 5.06; N, 29.23; P, 10.66.

EXAMPLE 32 9-(R)-(2-Phosphonomethoxypropyl)hypoxanthine

A solution of 9-(R)-(2-phosphonomethoxypropyl)adenine (400 mg, 1.4 mmol)and sodium nitrite (1.4 g, 20 mmol) in water (40 ml) was cooled in anice bath and conc. hydrochloric acid (2 ml) was added. The mixture wasstirred in an argon atmosphere at 0° C. for 3 h and then overnight at anambient temperature. The mixture was applied onto a column (100 ml)Dowex 50×8 (acid form) and the column eluted with water. The product waseluted with retention; the pertinent fraction was evaporated in vacuo,the residue codistilled with ethanol (2×50 ml) and the crystallineresidue filtered with ether. Yield, 250 mg (62%)9-(R)-(2-phosphonomethoxypropyl)hypoxanthine, UV-Spectrum (pH2): 1_(max)251 nm. For C₉H₁₃N₄O₅P (288.3) calc.: C, 37.50; N, 4.54; N, 19.44; P,10.77. found: C, 37.35; H, 4.55; N, 19.22; P, 10.86.

EXAMPLE 33 9-(S)-(2-Phosphonomethoxypropyl)hypoxanthine

A solution of 9-(S)-phosphonomethoxypropyl)adenine (400 mg, 1.4 mmol)and sodium nitrite (1.4 g, 20 mmol) in water (40 ml) was cooled in anice bath and conc. hydrochloric acid (2 ml) was added. Further work-upof the reaction was performed as described in Example 31. Yield, 66%9-(S)-(2-phosphonomethoxypropyl)hypoxanthine. UV-Spectrum (pH2): 1_(max)251 nm. For C₉H₁₃N₄O₅P (288.3) calc.: C, 37.50; H, 4.54; N, 19.44; P,10.77. found: C, 37.80; H, 4.65; N, 19.56; P, 10.55.

EXAMPLE 349-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-dimethylaminopurine

A solution of di(2-propyl)9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-chloropurine (0.50 g,prepared according to Example 26) in 20% dimethylamine in methanol isheated to 110° C. for 20 h in a pressure vessel and the solutionevaporated in vacuo. The residue in 50% aqueous methanol (20 ml) isapplied onto a column (50 ml) of Dowex 50×8 (H⁺-form) in 20% aqueousmethanol and the column washed with the same eluent until theUV-absorption dropped to the original value. The column is then washedwith 2.5% ammonia solution in 20% aqueous methanol and the UV-absorbingeluate taken to dryness, codistilled twice with ethanol (25 ml each) anddried over phosphorus pentoxide at 13 Pa. The resulting product istreated with acetonitrile (30 ml) and bromotrimethylsilane (3 ml)overnight at room temperature and the solution evaporated in vacuo.Water (50 ml) is added, the mixture alkalized by addition of conc.aqueous ammonia and the solution evaporated. Further work-up andpurification is performed essentially as described in Example 17. Yield,0.40 g (95%)9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-dimethylaminopurine, m.p.154-156° C., [α]_(D)=−10.6° (c=0.5, 0.1M HCl). ¹H-NMR spectrum(D₂O+NaOD): 1.165 d(3H), J_(3′,2′)=6.3 CH₃; 3.27 s (6H) N—CH₃; 3.47dd(1H), J_(P,CH)=9.5, J_(g)=12.9 and 3.65 dd(1H) J_(P,CH)=9.3,J_(g)=12.9, P—CH₂; 3.91 m, ΣJ=29.0 2′-CH; 4.06 dd(1H), J_(1″2′)=6.4,J_(g)=14.16 and 4.16 dd(1H), J_(1′2′)=3.7, J_(g)=14.16 1′-CH₂; 7.79s(1H), H-8. For C₁₁H₁₉N₆O₄P (330.3) calc. C, 40.00; H, 5.80; N, 25.44;P, 9.38. found C, 39.54; H, 5.75; N, 24.78; P, 8.92.

EXAMPLE 35 9-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-diethylaminopurine

A mixture of di(2-propyl)9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-chloropurine (0.50 g,prepared according to Example 26) and diethylamine (2 ml) in methanol(20 ml) is heated to 100° C. for 20 h in a pressure vessel and thesolution evaporated in vacuo. The residue in 50% aqueous methanol (20ml) is applied onto a column (50 ml) of Dowex 50×8 (H⁺-form) in 20%aqueous methanol and the column is washed with the same eluent until theUV-absorption dropped to the original value. The column is then washedwith 2.5% ammonia solution in 20% aqueous methanol and the UV-absorbingeluate taken to dryness, codistilled twice with ethanol (25 ml each) anddried over phosphorus pentoxide at 13 Pa. The resulting product istreated with acetonitrile (30 ml) and bromotrimethylsilane (3 ml)overnight at room temperature and the solution evaporated in vacuo.Water (50 ml) is added, the mixture alkalized by addition of conc.aqueous ammonia and the solution evaporated. Further work-up andpurification is performed essentially as described in Example 17. Yield,0.40 g (95%)9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-diethylaminopurine,m.p.162-164° C., [α]_(D)=−9.8° (c=0.5, 0.1M HCl). For C₁₃H₂₃N₆O₄P(358.4) calc. C, 43.56; H, 6.47; N, 23,45; P, 8.66. found C, 43.80; H,6.73; N, 23.78; P, 8.90.

EXAMPLE 36 9-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-butylaminopurine

A mixture of di(2-propyl)9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-chloropurine (0.50 g,prepared according to Example 26), butylamine (2.0 ml) and ethanol (20ml) is refluxed under exclusion of moisture for 6 h and evaporated invacuo. The work-up of the reaction mixture, following reaction withbromotrimethylsilane and isolation of the product is performedessentially as described in Example 34. Yield, 0.40 g (87%) of9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-butylaminopurine,m.p.140-142° C., [α]_(D)=−11.9° (c=0.5, 0.1M HCl). ¹H-NMR spectrum(D₂O+NaOD):1.18 d(3H), J_(3′,2′)=5.9 CH₃; 3.52 dd(1H), J_(P,CH)=9.8,J_(g)=12.5 and 3.67 dd(1H) J_(P,CH)=9.5, J_(g)=12.5, P—CH₂; 3.93 m,2′-CH; 4.05 dd(1H), J_(1″2′)=6.1, J_(g)=14.6 and 4.16 dd(1H),J_(1′2′)=3.5, J_(g)=14.6 1′-CH₂; 7.83 s(1H), H-8; butyl: 0.92 t(3H),J=7.3 CH₃; 1.38 br sext(2H), ΣJ=36.6 3-CH₂; 1.59 br pent(2H), ΣJ=28.32-CH₂; 3.43 br m(2H) 1-CH₂. For C₁₃H₂₄N₆O₄ P (359.4) calc. C, 43.44; H,6.73; N, 23.39; P, 8.64. found C, 43.31; H, 6.20; N, 23.57; P, 8.90.

EXAMPLE 379-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-(2-butyl)aminopurine

A mixture of di(2-propyl)9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-chloropurine (0.50 g,prepared according to Example 26), 2-butylamine (2.0 ml) and ethanol (20ml) is refluxed under exclusion of moisture for 8 h and evaporated invacuo. The work-up of the reaction mixture, following reaction withbromotrimethylsilane and isolation of the product is performedessentially as described in Example 34. Yield, 0.35 g (75%) of9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-(2-butyl)aminopurine,m.p.148-149° C., [α]_(D)=−14.5° (c=0.5, 0.1M HCl). ¹H-NMR spectrum(D₂O+NaOD): 1.17 d(3H), J_(3′,2′)=6.3, CH₃; 3.51 dd(1H), J_(P,CH)=9.5,J_(g)=12.5 and 3.63 dd (1H) J_(P,CH)=9.3, J_(g)=12.5, P—CH₂; 3.94 m,2′-CH; 4.08 dd(1M), J_(1″2′)=6.1, J_(g)=14.6 and 4.19 dd(1H),J_(1′2′)=3.5, J_(g)=14.6 1′-CH₂; 7.88 s(1H), H-8; 2-butyl: 0.94 t(3H),J=7.3+1.25 d(3H), J=6.6 CH₃; 1.61 br pent(2H), ΣJ=28.1 CH₂; 4.15 brm(1H) CH. For C₁₃H₂₄N₆O₄P (359.4) calc. C, 43.44; H, 6.73; N, 23.39; P,8.64. found C, 43.35; H, 6.59; N, 23.67; P, 8.68.

EXAMPLE 389-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-cyclopropylaminopurine

A mixture of di(2-propyl)9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-chloropurine (0.50 g,prepared according to Example 26), cyclopropylamine (2.0 ml) and ethanol(20 ml) is refluxed under exclusion of moisture for 12 h and evaporatedin vacuo. The work-up of the reaction mixture, following reaction withbromotrimethylsilane and isolation of the product is performedessentially as described in Example 34. Yield, 0.35 g (80%) of9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-cyclopropylaminopurine,m.p.178-179° C., [α]_(D)=−23.5° (c=0.5, 0.1M HCl). ¹H-NMR spectrum(D₂O+NaOD):1.21 d(3H), J_(3′2′)=6.1 CH₃; 3.56 dd(1H), J_(P,CH)=9.8,J_(g)=12.9 and 3.73 dd (1H) J_(P,CH)=9.8, J_(g)=12.9, P—CH₂; 3.96 m,2′-CH; 4.06 dd(1H), J_(1″2′)=6.6, J_(g)=14.4 and 4.18 dd(1H),J_(1′2′)=3.2, J_(g)=14.4 1′-CH₂; 7.87 s(1H), H-8; cyclopropyl: 2.84m(1H) CH; 0.70 m(2H)+0.94 m(2H) CH₂.C₁₂H₂₀N₆O₄P (343.4) calc. C, 41.97;H, 5.87; N, 24.48; P, 9.04. found C, 41.76; H, 6.05; N, 24.77; P, 9.21.

EXAMPLE 399-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-cyclopentylaminopurine

A mixture of di(2-propyl)9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-chloropurine (0.50 g,prepared according to Example 26), cyclopentylamine (2.0 ml) and ethanol(20 ml) is refluxed under exclusion of moisture for 12 h and evaporatedin vacuo. The work-up of the reaction mixture, following reaction withbromotrimethylsilane and isolation of the product is performedessentially as described in Example 34. Yield, 0.36 g (76%) of9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-cyclopentylaminopurine, m.p.167-170° C., [α]_(D)=−17.1° (c=0.5, 0.1M HCl). ¹H-NMR spectrum(D₂O+NaOD): 1.17 d(3H), J_(3′,2′)=6.3, CH₃; 3.67 dd(1H), J_(P,CH)=7.8,J_(g)=12.2 and 3.56 dd (1H) J_(P,CH)=9.3, J_(g)=12.2, P—CH₂; 3.97 brsext (1H), 2′-CH, ΣJ=29.1; 4.18 d(2H), J_(1′2′)=5.1, 1′-CH₂; 7.92 s(1H),H-8; cyclopentyl: 4.33 m(1H) CH; 2.00 m (2H)+1.70 m(2H) CH₂+1.60m(2H)+1.54 m (2H). C₁₄H₂₄N₆O₄P (371.4) calc. C, 45.27; H, 6.51; N, 22.63;P, 8.36. found C, 44.89; H, 6.45; N, 22.77; P, 8.23.

EXAMPLE 409-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-cyclohexylaminopurine

A mixture of di(2-propyl)9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-chloropurine (0.50 g,prepared according to Example 26), cyclohexylamine (2.0 ml) and ethanol(20 ml) is refluxed under exclusion of moisture for 10 h and evaporatedin vacuo. The work-up of the reaction mixture, following reaction withbromotrimethylsilane and isolation of the product is performedessentially as described in Example 34. Yield, 0.32 g (65%) of9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-cyclohexylaminopurine, m.p.164-165° C., [α]_(D)=−15.9° (c=0.5, 0.1M HCl). ¹H-NMR spectrum(D₂O+NaOD):1.12 d(3H), J_(3′,2′)=6.3; 3.43 dd(1H), J_(P,CH)=9.3,J_(g)=12.4 and 3.5 d (1H) J_(P,CH)=9.3, J_(g)=12.4, P—CH₂; 3.93 m,2′-CH; 4.10 dd(1H), J_(1″2′)=5.6, J_(g)=14.6 and 4.18 dd(1H),J_(1′2′)=4.4, J_(g)=14.6 1′-CH₂; 7.92 s(1H), H-8; cyclohexyl: 3.90 m(1H)CH; 1.15-1.42 m(5H)+1.62 m(1H)+1.75 m(2H)+1.95 m(2H) CH₂.C₁₅H₂₅N₆O₄P(384.4) calc. C, 46.86; H, 6.56; N, 21.87; P, 8.07. found C, 46.44; H,6.85; N, 22.07; P, 8.21.

EXAMPLE 41 9-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-pyrrolidinopurine

A mixture of di(2-propyl)9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-chloropurine (0.50 g,prepared according to Example 26), pyrrolidine (2.0 ml) and ethanol (20ml) is refluxed under exclusion of moisture for 6 h and evaporated invacuo. The work-up of the reaction mixture, following reaction withbromotrimethylsilane and isolation of the product is performedessentially as described in Example 34. Yield, 0.35 g (78%) of9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-pyrrolidinopurine,m.p.181-182° C., [α]_(D)=−17.4° (c=0.5, 0.1M HCl). ¹H-NMR spectrum(D₂O+NaOD):1.21 d(3H), J_(3′,2′)=6.1, CH₃; 3.57 dd(1H), J_(P,CH)=9.5,J_(g)=12.2 and 3.65 dd (1H) J_(P,CH)=9.5, J_(g)=12.2, P—CH₂; 3.98 brsext(1H) 2′-CH; 4.18 d(2H), J_(1′2′)=4.9, 1′-CH₂; 7.85 s(1H), H-8;pyrrolidin-1-yl: 3.41 br(2H) and 3.75 br(2H) N—CH₂; 1.93br(2H)+2.00br(2H) C—CH₂. C₁₃H₂₁N₆O₄P (356.4) calc. C, 43.81; H, 5.94; N, 23.58; P,8.71. found C, 43.45; H, 6.17; N, 23.87; P, 8.82.

EXAMPLE 42 9-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-piperidinopurine

A mixture of di(2-propyl)9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-chloropurine (0.50 g,prepared according to Example 26), piperidine (2.0 ml) and ethanol (20ml) is refluxed under exclusion of moisture for 3 h and evaporated invacuo. The work-up of the reaction mixture, following reaction withbromotrimethylsilane and isolation of the product is performedessentially as described in Example 34. Yield, 0.40 g (84%) of9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-piperidinopurine,m.p.154-156° C., [α]_(D)=−0.8° (c=0.5, 0.1M HCl). ¹H-NMR spectrum(D₂O+NaOD):1.14 d(3H), J_(3′,2′)=6.1, CH₃; 3.44 dd(1H), J_(P,CH)=9.0,J_(g)=12.4 and 3.55 dd (1H) J_(P,CH)=9.3, J_(g)=12.4, P—CH₂; 3.93 m(1H)2′-CH; 4.09 d(2H) J_(1″2′)=6.1, J_(g)=14.4 and 4.17 dd(1H),J_(1′2′)=4.1, J_(g)=14.4 1′-CH₂; 7.88 s(1H), H-8; piperidin-1-yl: 3.95br t(4H), J=5.4 N—CH₂; 1.60 m (4H)+1.69 m(2H) C—CH₂. C₁₄H₂₃N₆O₄P (370.4)calc. C, 45.40; H, 6.26; N, 22.69; P, 8.36. found C, 45.68; H, 5.94; N,22.46; P, 8.41.

EXAMPLE 43 9-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-morpholinopurine

A mixture of di(2-propyl)9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-chloropurine (0.50 g,prepared according to Example 26), morpholine (2.0 ml) and ethanol (20ml) is refluxed under exclusion of moisture for 2 h and evaporated invacuo. The work-up of the reaction mixture, following reaction withbromotrimethylsilane and isolation of the product is performedessentially as described in Example 34. Yield, 0.45 g (94.5%) of9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-morpholinopurine,m.p.160-162° C., [α]_(D)=+7.1° (c=0.5, 0.1M HCl). ¹H-NMR spectrum(D₂O+NaOD):1.15 d(3H), J_(3′,2′)=6.1; 3.50 dd(1H), J_(P,CH)=9.8,J_(g)=12.9 and 3.68 dd (1H) J_(P,CH)=9.3, J_(g)=12.9, P—CH₂; 3.90 m(1H)2′-CH; 4.05 d(2H) J_(1″2′)=6.6, J_(g)=14.4 and 4.18 dd(1H),J_(1′2′)=3.2, J_(g)=14.4 1′-CH₂; 7.81 s(1H), H-8; morpholin-1-yl: 4.03br t(4H), J=4.5 N—CH₂; 3.80 br t(4H) C—CH₂.C₁₃H₂₁N₆O₅P (372.3) calc. C,41.94; H, 5.69; N, 22.57; P, 8.32. found C, 42.03; H, 5.66; N, 22.16; P,8.62.

EXAMPLE 44 9-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-benzylaminopurine

A mixture of di(2-propyl)9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-chloropurine (0.50 g,prepared according to Example 26), benzylamine (2.0 ml) and ethanol (20ml) is refluxed under exclusion of moisture for 6 h and evaporated invacuo. The work-up of the reaction mixture, following reaction withbromotrimethylsilane and isolation of the product is performedessentially as described in Example 34. Yield, 0.45 g (90%) of9-(R)-(2-phosphonomethoxypropyl)-2-amino-6-benzylaminopurine,m.p.158-160° C., [α]_(D)=−4.9° (c=0.5, 0.1M HCl). ¹H-NMR spectrum(D₂O+NaOD):1.13 d(3H), J_(3′,2′)=5.9; 3.52 dd(1H), J_(P,CH)=10.3,J_(g)=12.0 and 3.68 dd (1H) J_(P,CH)=10.0, J_(g)=12.0, P—CH₂; 3.86 m(1H)2′-CH; 3.99 d(2H) J_(1″2′)=5.6, J_(g)=14.4 and 4.09 dd(1H),J_(1′2′)=3.5, J_(g)=14.4 1′-CH₂; 7.77 s(1H), H-8; arom.protons: 7.22m(5H); 4.58 br s(2H) benzyl-CH₂. C₁₆H₂₁N₆O₄P (392.3) calc. C, 48.98; H,5.39; N, 21.42; P, 7.89. found C, 49.16; H, 5.37; N, 21.23; P, 7.86.

EXAMPLE 45 9-(S)-(2-Phosphonomethoxypropyl)-8-azaquanine and8-(S)-(2-Phosphonomethoxypropyl)-8-azaguanine

A mixture of 8-azaguanine (3.5 g), dimethylformamide (35 ml) anddimethylformamide dineopentyl acetal (15 ml) is heated at 80° C. 16 hunder exclusion of moisture. After cooling at room temperature, theprecipitated product is filtered by suction, washed with ethanol andether and dried in vacuo. Yield, 3.1 g (65%)N2-dimethylaminomethylene-8-azaguanine, HPLC pure.

The mixture of this compound (2.1 g, 10 mmol), cesium carbonate (1.75 g,5.4 mmol) and(S)-2-[(di(2-propyl)phosphonylmethoxy]-1-toluenesulfonyloxypropane indimethylformamide (40 ml) is stirred for 4 h at 100° C. under exclusionof moisture. The mixture is filtered while hot, evaporated at 40° C./13Pa and the residue treated with a mixture of methanol and conc.aqueousammonia (1:1, 200 ml) overnight at ambient temperature. The solvents areevaporated in vacuo and the residue chromatographed on a column ofsilica gel (200 ml) in methanol-chloroform mixture (5:95). Thefluorescent product (Rf=0.42, TLC in methanol-chloroform, 1:9, silicagel plate), amorphous foam, yield 0.9 g (23%) is dried in vacuo andtreated with acetonitrile (25 ml) and bromotrimethylsilane (2.5 ml)overnight at room temperature. The work-up of the mixture is performedas described in Example 34. The product is isolated by ion exchangechromatography on Dowex 50×8 (H⁺-form) and crystallized from water.Yield, 0.45 g.

Further elution of the silica gel column affords the 9-isomer (Rf=0.36,TLC in methanol-chloroform, 1:9, silica gel plate) in the yield of 0.9 g(23%). Conversion by bromotrimethylsilane in acetonitrile (Example 34)gives after deionization and crystallization from water9-(S)-(2-phosphonomethoxypropyl)-8-azaguanine (0.50 g, HPLC pure).

EXAMPLE 46 9-(R)-(2-Phosphonomethoxypropyl)-8-azaquanine,8-(R)-(2-Phosphonomethoxypropyl)-8-azaquanine and7-(R)-(2-Phosphonomethoxypropyl)-8-azaquanine

The reaction is performed essentially as described for the(S)-enantiomers in Example 44. After the work-up of the condensationmixture with aqueous methanolic ammonia the crude mixture ofbis(2-propyl)esters is applied onto a column of Dowex 50×8 (H+-form)(150 ml) and the column eluted with 20% aqueous methanol. TheUV-absorbing fraction is taken down in vacuo and dried affording the9-isomer as an amorphous foam. The residue is treated with acetonitrile(30 ml) and bromotrimethylsilane (3 ml) overnight, evaporated in vacuo,the residue dissolved in 2.5% ammonia and reevaporated in vacuo. Thisresidue is applied onto a column (100 ml) Dowex 1×2 (acetate form) andwashed with water (1 l) and with 1 M acetic acid (500 ml). The eluatesare discarded and the resin extracted on filter with boiling water (500ml). This eluate is evaporated in vacuo and the residue crystallizedfrom water (poorly soluble) to afford the 9-(R)-isomer (0.50 g). ForC₈H₁₃N₆O₅P (304.2) calculated: 31.59%; C, 4.31%; H, 27.62%;N, 10.18%;P.found 32.10%;C, 4.35%; H, 27.44%; N, 10.30%; P.

Further elution of Dowex 50 column with 2.5% aqueous ammonia gives anUV-absorbing fraction which is evaporated in vacuo, dried and treatedwith acetonitrile (20 ml) and bromotrimethylsilane (2 ml). The reactionmixture is evaporated and the residue dissolved by the addition of 5%aqueous ammonia (100 ml), and the mixture is deionized on a column (100ml) Dowex 50×8 (H⁺-form). The ammonia eluate affords gel forming mixturewhich is dissolved in water by addition of ammonia and applied onto acolumn of Sephadex A-25 (150 ml) in 0.02 M triethylammonium hydrogencarbonate. The column is eluted with a linear gradient of the samebuffer (0.02-0.20 M, 1 l each) to give the main fraction consisting ofthe mixture of the 7- and 8-isomer (E_(Up) 0.92, fluorescent spot). Theresidue after codistillation with methanol is applied onto a column (20ml) Dowex 1×2 (acetate), the column washed with water (100 ml) and theproduct eluted with 1 M acetic acid. After evaporation in vacuo,codistillation with water and trituration with ethanol the product isfiltered, washed with ethanol and ether, and dried to afford 0.50 g ofthe mixture of 7-isomer and 8-isomer in the ratio 1:4 (by ¹³C-NMR). The7- and 8-regioisomers were separated by chromatography on DEAE SephadexA25, using elution by a 0.02 to 0.2 molar gradient of aqueoustriethylammonium hydrocarbonate at pH 7.5. For C₈H₁₃N₆O₅P (304.2)calculated: 31.59%; C, 4.31%; H, 27.62%;N, 10.18%;P. found 32.10%;C,4.35%; H, 27.44%; N, 10.30%; P. ¹H-NMR (D₂O+NaOD): 8-Isomer: 4.65 2×dd,2H (J_(1′2′)=5.4,J_(1″2′)=5.1,J_(g)=14.0) 1′-CH₂; 4.17 br sext, 1H(J=29.5) 2′-CH; 3.52 dd, 1H (J_(PCH)=9.7, J_(g)=12.2)+3.47 dd, 1H(J_(PCH)=9.0, J_(g)=12.2) P—CH₂; 1.18 d, 3H (J_(3′2′)=6.3); 7-Isomer4.76 2×dd, 2H (J_(1′2′ J) _(1″2′)=5.2, J_(g)=14.0) 1′-CH₂; 4.13 br sext,1H (J=29.5) 2′-CH; 3.50 m, P—CH₂; 1.16 d, 3H (J_(3′2′)=6.3).

EXAMPLE 47 9-(R)-(2-Phosphonomethoxypropyl)-8-aza-2,6-diaminopurine and8-(R)-(2-Phosphonomethoxypropyl)-8-aza-2,6-diaminopurine

A suspension of 8-aza-2,6-diaminopurine hemisulfate (25 mmol) in water(100 ml) is stirred under addition of Dowex 50×8 (H⁺-form) untildissolution, the suspension was poured onto a column of the same cationexchanger (100 ml) and the column is washed with water until neutral.The resin is then suspended in water (200 ml) and treated with aqueousammonia until alkaline, filtered and washed with boiling water (total, 1l). The filtrate and washings are taken to dryness in vacuo, the residuecodistilled with ethanol (2×50 ml) and the obtained free8-aza-2,6-diaminopurine filtered from ether, washed with the samesolvent and dried over phosphorus pentoxide in vacuo.

A suspension of this compound (3.02 g, 20 mmol) and cesium carbonate(3.3 g, 10 mmol) in dimethylformamide (60 ml) is heated at 100° C. for 1h and a solution of(R)-2-[(di(2-propyl)phosphonylmethoxy]-1-toluenesulfonyloxypropane (8.6g, 21 mmol) in dimethylformamide (30 ml) is added over 15 min understirring. The heating and stirring is then continued for additional 16h, the mixture stripped of the solvent in vacuo and the residueextracted with boiling chloroform (total, 300 ml). The extract ischromatographed on a column (250 ml) silica gel in chloroform and thecolumn eluted with chloroform-methanol mixture (95:5). The elutionaffords di(2-propyl)9-(R)-(2-phosphonomethoxypropyl)-8-aza-2,6-diaminopurine (R_(F)0.70, TLCon silica gel, chloroform-methanol, 4:1) which after evaporation of therelevant fractions and crystallization from ethyl acetate-petroleumether gives 1.75 g (22.5%) of a crystalline material, m.p.120-122° C.,[α]_(D)=4.7° (c=0.5, 0.1M HCl). For C₁₄H₂₆N₇O₄P (387.5) calculated: C,43.40; H, 6.76; N, 25.31; P, 8.01. found C, 43.07; H, 6.80; N, 25.21;and 8.02%; P. NMR-Spectrum:1.10+1.12+1.14+1.16+1.17, 5×d (3H each),J=6.1), CH₃; 4.11 pent d (ΣJ=29.5) 2′-CH; 4.28 2×dd, 1H (J_(1″2′)=4.90,J_(g)=14.4) 1′-CH₂; 4.34 dd,1H (J_(1′2′)=7.1, J_(g)=14.4) 2′-CH; 3.65dd, 1H (J_(PCH)=9.0, J_(g)=12.7)+3.74 dd, 1H (J_(PCH)=9.5, J_(g)=12.27)P—CH₂; 4.43 dq (1H) (J=6.1)+4.47 (J=6.3, J_(P)—O—CH=7.8) P—OCH;7.35+7.70, 2×br (2×1H) NH₂; 6.37 brs (2H) NH₂.

This product is treated with acetonitrile (25 ml) andbromotrimethylsilane (2.5 ml) overnight at room temperature and thesolution evaporated in vacuo. Water (50 ml) is added, the mixturealkalized by addition of conc. aqueous ammonia and the solutionevaporated. Further work-up and purification is performed essentially asdescribed in Example 17. Yield, 0.90 g (65.5%)9-(R)-(2-phosphonomethoxypropyl)-2,6-diamino-8-azaadenine, m.p. 238-242°C., [α]_(D)=+5.6° (c=0.5, 0.1M HCl). ¹H-NMR spectrum (D₂O+NaOD): 1.17d(3H),(J_(3′,2′)=6.3) CH₃; 3.50 dd(1H), J_(P,CH)=9.1, J_(g)=12.2 and3.59 dd(1H) J_(P,CH)=9.3, J_(g)=12.2, P—CH₂; 4.08 m, ΣJ=30.0 2′-CH; 4.45dd(1H), J_(1″2′)=5.4, J_(g)=14.9 and 4.49 dd(1H), J_(1′2′)=5.6,J_(g)=14.9 1′-CH₂. For C₈H₁₄N₇O₄P (305.3) calc. C, 31.47; H, 4.62; N,32,12; P, 10.17. found C, 31.71; H, 5.02; N, 31.88; P, 9.96.E_(Up)(pH7.5)=0.85.

Further elution of the silica gel column gives 1.40 g (18%) ofdi(2-propyl) 8-(R)-(2-phosphonomethoxypropyl)-8-aza-2,6-diaminopurine(R_(F)0.50, TLC on silica gel, chloroform-methanol, 4:1), m.p.148-150°C. (ethyl acetate-petroleum ether), [α]_(D)=−43.7° (c=0.5, 0.1M HCl).For C₁₄H₂₆N₇O₄P (387.5) calculated: C, 43.40; H, 6.76; N, 25.31; P,8.01. found C, 43.15; H, 6.75; N, 25.16; and 7.96%; P.NMR-Spectrum:1.10+1.11+1.14+1.16+1.18, 5×d (3H each), J=6.1) CH₃; 4.17pent d (ΣJ=31.0) 2′-CH; 4.50 dd, 1H (J_(1″2′)=6.60, J_(g)=13.9)+4.53 dd,1H (J_(1′2′)=5.4, J_(g)=13.9) 1′-CH₂; 4.47+4.43 2×dq, 2H (J_(P—OCH)=7.6,JCH,CH₃=6.1) P—OCH; 3.63 dd, 1H (J_(PCH)=9.0, J_(g)=12.7)+3.75 dd, 1H(J_(PCH)=9.5, J_(g)=12.7) P—CH₂; 7.50+6.08, 2×br (2×2H) NH₂. Thereaction with bromotrimethylsilane is performed essentially as describedfor the 9-isomer; yield, 0.80 g (72.5%)8-(R)-(2-phosphonomethoxypropyl)-8-aza-2,6-diaminopurine, m.p. 238-240°C., [α]_(D)=−23.5° (c=0.5, 0.1M HCl). ¹H-NMR spectrum (D₂O+NaOD): 1.21d(3H), (J_(3′,2′)=6.3) CH₃; 3.50 dd(1H), J_(P,CH)=9.2, J_(g)=12.2 and3.58 dd(1H) (J_(P,CH)=9.4, J_(g)=12.2) P—CH₂; 4.17 m, ΣJ=29.3 2′-CH;4.70 d(2H), J_(1′2′)=5.2) 1′-CH₂. For C₈H₁₄N₇O₄P (305.3) calc. C, 31.47;H, 4.62; N, 32.12; P, 10.17. found C, 30.74; H, 4.55; N, 29.90; P,10.16. E_(Up)(pH7.5)=0.85.

EXAMPLE 48 9-(R)-(2-Phosphonomethoxypropyl)-6-mercaptopurine

Sodium hydride (0.40 g, 60% dispersion in paraffin, 10 mmol) is added toa solution of 6-chloropurine (1.55 g, 10 mmol) in dimethylformamide (25ml) and the mixture stirred for 1 h at ambient temperature. A solutionof (R)-2-[(di(2-propyl)phosphonylmethoxy]-1-toluenesulfonyloxypropane(6.5 g, 15.9 mmol) in dimethylformamide (50 ml) is added and the mixturestirred at 60° C. for 8 h. The mixture is then stripped off the solventin vacuo and the residue extracted with hot chloroform (total, 250 ml).The extract is then evaporated in vacuo and the residue chromatographedon a column (250 ml) of silica gel in chloroform. The product is elutedwith chlorofom-methanol (95:5) and the relevant fractions containingproduct were evaporated to dryness. Yield, 2.35 g (60%) of the oilydi(2-propyl) 8-(R)-(2-phosphonomethoxypropyl)-6-chloropurine (R_(F)0.70,TLC on silica gel, chloroform-methanol, 4:1), m.p.148-150° C. (ethylacetate-petroleum ether), [α]_(D)=−43.7° (c=0.5, 0.1M HCl). ForC₁₅H₂₄ClN₄O₄P (390.9): Mass spectrum:391(M⁺), 348 (M-ipr), 306(M-2×iPr); NMR-Spectrum: 1.05 d (3H), J=6.1) CH₃; 4.02 pent d (ΣJ=28.9)2′-CH; 4.30 dd, 1H (J_(1″2′)=7.00, J_(g)=14.3)+4.45 dd, 1H(J_(1′2′)=3.6, J_(g)=14.3) 1′-CH₂; 4.49 m, 2H (J_(P—OCH)=7.6) P—OCH;3.68 dd, 1H (J_(PCH)=9.8, J_(g)=13.7)+3.82 dd, 1H(J_(PCH)=9.2,J_(g)=13.7) P—CH₂; 1.12+1.13 (3×d, 4×3H), J=6.1, J=6.3) CH₃ (2-propyl);8.61+8.77, 2×s, 2H, H-2+H-8.

This product is treated with thiourea (2 g) in ethanol at reflux for 1h, the solution is alkalized with triethylamine, taken down. to drynessand the residue extracted with chloroform (200 ml). The extract isevaporated in vacuo and the residue (R_(F)0.63, TLC on silica gel,chloroform-methanol, 4:1) dried in vacuo. Acetonitrile (40 ml) andbromotrimethylsilane (4 ml) is added and the mixture stirred tilldissolution. The mixture is left to stand overnight at room temperature,taken down to dryness in vacuo and dissolved in water (100 ml) byalkalization with conc.aqueous ammonia. The alkaline solution is thenevaporated in vacuo and the residue in water (20 ml) (alkalized byammonia) is applied onto a column (150 ml) Sephadex A-25 equilibratedwith 0.05 M triethylammonium hydrogen carbonate (pH 7.5). The column iseluted with the same buffer until the absorption of the eluate drops tothe original value and then with linear gradient (0.02M-0.2Mtriethylammonium hydrogen carbonate (pH 7.5) (1l each). The main UVabsorbing fraction is taken down to dryness and codistilled withmethanol (5×50 ml) in vacuo. The residue is applied in 10 ml water on acolumn (50 ml) Dowex 1×2 (acetate form), the column washed with waterand the ionex stirred in 10% aqueous formic acid (200 ml) for 15 min.The suspension is filtered and the resin washed repeatedly with boilingwater (total, 1 l). The filtrates gaffords on concentration in vacuo andrecrystallization from water9-(R)-(2-phosphonomethoxypropyl)-6-thiopurine (0.90 g, 49%),m.p.156-158° C., [α]_(D)=−1.7° (c=0.5, 0.1HCl). ¹H-NMR-Spectrum(D₂O+NaOD): 1.25 d(3H),(J_(3′,2′)=5.4) CH₃; 3.57 dd(1H), J_(P,CH)=9.5,J_(g)=12.2 and 3.79 dd(1H) (J_(P,CH)=9.5, J_(g)=12.2) P—CH₂; 4.02 m2′-CH; 4.31 d(2H) (J_(1″2′)=6.8)+4.52 d, 2H (J_(1′2′)<2.0, J_(g)=14.4)1′-CH₂; 8.35+8.72, 2×s (2H) H-2+H-8. For C₉H₁₃N₄O₄PS (304.0) calc. C,35.52; H, 4.31; N, 18.42; P, 10.19; S, 10.50. found C, 35.34; H, 4.70;N, 18.26; P, 10.76.

EXAMPLE 49 9-(R)-(2-Phosphonomethoxypropyl)-N1,N6-ethenoadenine

A solution of 9-(R)-(2-phosphonomethoxypropyl)adenine (0.40 g) in 1Mchloroacetaldehyde solution in water (20 ml) is incubated at 37° C. for48 h and evaporated in vacuo. The residue in water (10 ml) is applied ona column (250 ml) octadecylsilica gel (20-30 μ) and washed with water (3ml/min). The fractions (20 ml) are analyzed by HPLC in 0.05 Mtriethylammonium hydrogen carbonate pH 7.5 and the appropriate fractionspooled and taken down in vacuo. The product is triturated with ethanoland filtered. Yield, 0.35 g (80%), m.p.180-182° C., [α]_(D)=−25.6°(c=0.5, 0.1M HCl). For C₁₁H₁₄N₅O₄P (311.3) calc. C, 42.44; H, 4.53; N,22.50; P, 9.97. found C, 42.30; H, 4.75; N, 22.24; P, 10.25.

EXAMPLE 50 Evaluation Against Human Immunodeficiency Virus (HIV) andMoloney Murine Sarcoma Virus (MSV) in Vitro

The activity of the compounds against HIV-1 and HIV-2 inducedcytopathicity was examined in human lymphocyte MT-4 cells. The cells(250 000 cells/ml) were infected with 100 CCID₅₀ (1 CCID is a virusquantity which causes cytopathicity effect in 50% of the cells under theexperimental conditions) of HIV-1 or HIV-2 and added to 200 μl-wells ofa microtiter plate containing different dilutions of the test compounds.The infected cell cultures were then incubated at 37° C. for 5 days in ahumidified CO₂-controlled incubator. Then, the cytopathicity of thevirus was examined by determination of MT-4 cell viability by trypanblue dye staining. The results are summarized in Table 1 in comparisonwith the data on the prototype compounds.

Also shown in Table 1 are results of testing the activity of thecompounds against MSV-induced transformation in murine embryo fibroblastC3H/3T3 cells. The cells were seeded in 1-ml-wells of a 48-wellmicrotiter plate and exposed to 80 PFU (plaque forming units) for 60-90minutes. Then, the virus was removed and culture medium containingappropriate concentrations of the test compounds were added (1 ml perwell). At day 6 post infection, MSV-induced transformation of the cellculture was examined microscopically. The results are summarized inTable 1 in comparison with the data on the prototype compounds.

TABLE 1 Anti-retrovirus activity of the (S)- and (R)-enantiomers of thecompounds of Formula I in comparison with other acyclic nucleosidephosphonates. MT-4 C3H/3T3 EC50^(a) CC50^(b) EC50^(c) MIC^(d) (μg/ml)(μg/ml) (μg/ml) (μg/ml) Compound HIV-1 HIV-2 MSV (S)-PMPA 78 63 >100120 >100 (R)-PMPA 1.7 1.4 >100 0.99 >100 (S)-PMPDAP 2.0 4.0 >1002.9 >100 (R)-PMPDAP 0.05 0.06 >100 0.14 >100 (S)-PMPG 1.2 1.3 45 0.95 8(R)-PMPG 1.8 1.7 >100 0.15 40 (R)-9-PMP-8-azaA 2.42 ± 1.75 ± 0.43 ± 0.910.2 0.24 (R)-9-PMP-6-thioPu >100 >100 18 ± 10(R)-7/8PMP-8-azaG* >0.16 >0.16 1.1 ± 0.6 (R)-9-PMP-6- >100 >100 12.6 ±piperidino-DAP 10 (R)-9-PMP-6- >100 >100 6.1 ± morpholino-DAP 2.3(R)-9-PMP-6- 8.0 ± 7 ± 1.4 ± cyclohexyl-DAP 2 2.6 1.2 (R)-9-PMP-6- 10.3± 8 ± 0.3 ± benzyl-DAP 1.4 2.9 0.11 (R)-9-PMP-6- 2.3 ± 4.2 ± 3.25 ±dimethyl-DAP 0.2 2.8 1.44 (R)-9-PMP-6-butyl-DAP 13.1 ± 9.8 ± 3.27 ± 4.34.9 1.3 (R)-9-PMP-6- 30 ± 19 25 ± 15 3.5 ± (2-butyl)-DAP 0.3(R)-9-PMP-6-thioG >100 >100 3.94 ± 2.13 PMEA 2 2 67 2 >100 (S)-FPMPA 2.72.6 >100 1.5 >100 (R)-FPHPA 83 54 >100 >100 >100 (S)-FPMPDAP 4.83.3 >100 1.7 >100 (R)-FPMPDAP 1.4 1.5 >100 1.7 >100 ^(a)Compoundconcentration required to inhibit HIV-induced cytopathicity in MT-4cells by 50%; ^(b)Compound concentration required to reduce MT-4 cellviability by 50%; ^(c)Compound concentration required to inhibitMSV-induced C3H/3T3 cell transformation by 50%; ^(d)Compoundconcentration that results in a microscopic alteration of the cellculture morphology. Abbreviations FPMPN-(3-fluoro-2-phosphonomethoxypropyl)derivative of the Formula 4; PMEN-(2-phosphonomethoxyethyl) derivative of the Formula 3; PMPN-(2-phosphonomethoxypropyl) derivative of the Formula I; A adenine, DAP2,6-diaminopurine, G guanine. *Regioisomeric mixture

Conclusions

(1) Most of the resolved compounds of the Formula I examined showedmarked anti-HIV activity in vitro. HIV-1 and HIV-2 did not differ intheir sensitivity to the test compounds.

(2) (R)-PMPA was markedly inhibitory to retrovirus replication at 1-2μg/ml and non-toxic to the cells at 100 mg/ml. Its selectivity index(ratio cytotoxic dose/antivirally active dose) proved superior over thatof the prototype compound PMEA. The (S)-enantiomer of PMEA was devoid ofmarked antiretroviral activity.

(3) (R)-PMPDAP was exquisitely inhibitory to retrovirus replication(EC₅₀ 0.01-0.1 μg/ml) and non-toxic to the cells at 100 μg/ml. It provedsuperior over PMEA and other prototype compounds in terms of bothantiviral activity and lack of toxicity. Its selectivity index was >2000 for HIV-1 and HIV-2.

EXAMPLE 51 Treatment of Moloney Murine Sarcoma Virus (MSV) Infection inMice by Intraperitoneal Administration

Two gram newborn NMRI mice were injected intramuscularly in the lefthind leg with 50 μl of 250-fold diluted stock preparation of Moloneymurine sarcoma virus. Starting 2-4 hours before virus infection, eachanimal was injected intraperitoneally in groups of 10 with a single doseof test compound with 50, 20 or 10 mg/kg of the resolved compounds ofthe Formula I or prototype compounds (for abbreviations, see Footnote toTable 1); compounds (R)-PMPA and (R)-PMPDAP were administered also atthe dose of 5 and 2 mg/kg. Another group of mice (20 animals) wasadministered RPMI-1640 medium as placebo. All compounds were solubilizedin RPMI-1640 medium. The mice were observed daily for 20 days and theday of tumor initiation and the day of animal death was recorded foreach animal. Statistical analyses were performed by calculating thestandard deviation. The summarized results are shown in the Table 2.

TABLE 2 Inhibitory effect of (S)- and (R)-enantiomers of the compoundsof the Formula I and prototype acyclic nucleoside phosphonatesadministered by intraperitoneal route on MSV-induced tumor formation andassociated death in NMRI mice. Dose Number Mean day of Mean day ofCompound (mg/kg) of mice tumor initiation^(a)) animal death^(b))(S)-PMPA 50 20 5.8 ± 0.63 12.4 ± 0.84 20 20 4.5 ± 0.71 10.9 ± 0.88 10 204.7 ± 0.95 10.9 ± 0.88 (R)-PMPA 50 10 >20 (100%) >20 (100%) 20 10 13.5 ±3.5 (80%) >20 (100%) 10 20 12.9 ± 2.2 (75%) 18.3 ± 1.10 (85%)  5 10 7.11± 1.5 (10%) 14.4 ± 0.47 (20%)  2 10 5.3 ± 1.1 12.6 ± 1.26 (R)-PMPDAP 2019 11 (95) 18 (95) 10 20 11.5 (90) 18.5 (90)  5 20 12.8 (70) 16.5 (90) 2 20 11 (36) 15 (70) PMEA 50 10 9.0 (90%) 16.0 (90%) 20 30 10.6 ± 2.0(44%) 14.7 ± 1.8 (66%) 10 20 9.8 ± 1.9 (24%) 14.2 ± 2.5 (43%) (S)-FPMPA50 10 >20 (100 %) >20 (100%) 20 20 11 ± 2.7 (31%) 17.2 ± 2.2 (55%) 10 207.7 ± 2.4 13.6 ± 2.8 (40%) (R)-FPMPA 50 10 4.7 ± 0.67 11.2 ± 0.92 20 104.3 ± 0.48 10.4 ± 0.52 (S)-FPMPDAP 50 10 11.0 ± 2.1 (17%) 16.5 ± 0.71(67%) 25 10 8.3 ± 1.8 14.6 ± 2.2 10  6 8.5 ± 2.6 16.7 ± 3.2 (33%)(R)-FPMPDAP 50 20 7.75 ± 1.3 13.9 ± 1.4 (10%) 25 20 7.7 ± 1.9 14.1 ± 1.5(15%) 10 20 5.6 ± 1.0 12.0 ± 1.0 Control  0 40 4.65 ± 0.81 10.7 ± 1.2^(a))Values in parentheses represent percentages of MSV-infected micewithout tumor at day 20 post infection. ^(b))Values in parenthesesrepresent percentages of MSV-infected mice that were still alive at day20 post infection.

While (S)-enantiomer of PMPA (and FPMPA) has no marked antiretroviralactivity in vivo at the dose of 50 mg/kg, (R)-PMPA, (R)-PMPDAP provedhighly effective in inhibiting tumor initiation and prolonging thelife-span of MSV-infected mice. A single (R)-PMPA dose of 50 mg/kgafforded full protection against MSV-induced tumor development. At lowerdoses, this compound proved superior over (S)-FPMPA in postponing theday of tumor initiation and the mean day of animal death. A single(R)-PMPDAP dose of 10-20 mg/kg gave virtually full protection of theanimals (90-95%) against MSV-induced tumor development; at a dose of 2mg/kg, significant prevention of tumor formation (in 36% of the animals)and 70% long time-survivors were observed.

Conclusion

(1) (R)-PMPA proved markedly effective in increasing the mean day oftumor initiation and animal death at the single dose of 10-50 mg/kg. Itis superior in these assays over the prototype compound PMEA.

(2) (R)-PMPDAP was one of the most active anti-Msv compound of theseries examined in vivo. It proved five-fold superior over (R)-PMPA. Itcontrasts to the FPMP-series where the adenine derivative is more activein the assays than the diaminopurine counterpart.

(3) The in vivo activity of the compounds of the Formula I are inagreement with their antiviral activities against HIV and MSV in vitro.

EXAMPLE 52 Treatment of Moloney Murine Sarcoma Virus (MSV) Infection inMice by Oral Administration

Three-week-old NMRI mice (about 10 grams body weight) were injectedintramuscularly in the left hind leg with 50 μl of 20-fold diluted stockpreparation of Moloney murine sarcoma virus. Starting 2-4 hours beforevirus infection, six animals received an orally administered testcompound twice a day at 100 mg/kg(total dose) daily for five subsequentdays. The control (placebo) group consisted of 14 animals. Theexperiment was evaluated as described in Example 35. The summarizedresults are given in Table 3.

TABLE 3 Number of Mean day of mice Number of tumor developing Compoundmice initiation tumor (%) (R)-PMPDAP  6 7.5 ± 1.0*⁾  67 Placebo(control) 14 5.0 ± 0.0 100 *⁾p < 0.005 (two-sided Student's t-test).

At the dose of 100 mg/kg/day, (R)-PMPDAP increased the mean day of tumorinitiation by 50%; only 67% of the mice developed a tumor.

What is claimed is:
 1. A compound of the formula:

including salts of such compounds, wherein said compound of Formula IAis substantially free of its enantiomer and wherein B is (a) anunsubstituted purine moiety, (b) a substituted purine moiety substitutedindependently at the 2 and/or 6 and/or 8 position by amino, halogen,hydroxy, alkoxy, alkylamino, dialkylamino, aralkylamino, pyrrolidino,morpholino, piperidino, benzoylamino, azido, mercapto or alkylthio, or(c) the 8-aza analog thereof, and wherein B is other than guanine or2-amino-6-halopurine; R is H; and aryl in aralkylamino is a 6-10Caromatic group.
 2. The compound of claim 1 of formula IA wherein B isadenine, 2,6-diaminopurine, 2-aminopurine, 8-bromoadenine,6-mercaptopurine, 6-thioguanine, 2-methylthioadenine, 8-azaadenine,8-azaguanine, or 8-aza-2,6-diaminopurine.
 3. The compound of claim 2wherein B is adenine, 8-azaguanine or 2,6-diaminopurine.
 4. A compoundof claim 3 wherein B is 2,6-diaminopurine.
 5. A method to prepare acompound of the formula:

substantially free of its enantiomer wherein B is as defined in claim 1,which method comprises hydrolyzing a compound of the formula

which is substantially free of its enantiomer to remove R groups whereinR is independently alkyl(1-6C), aryl or aralkyl by treating with ahalotrialkylsilane in a polar aprotic solvent medium.
 6. The method ofclaim 5 wherein both R are 2-propyl.
 7. The method of claim 5 whereinthe compound of Formula VIIA is prepared by a process which comprisesdeprotecting a compound of the formula:

substantially free of its enantiomer wherein B′ is a protected form of Bas defined herein by treating said compound of Formula VIA with at leastone deprotecting reagent.
 8. The method of claim 7 wherein said compoundof Formula VIA is prepared by a process which comprises reacting acompound of the formula:

substantially free of its enantiomer wherein B′ is a protected form of Bas herein defined with a compound of the formula LvOCH₂P(O)(OR)₂  (IV)wherein LvO is a leaving group, and each R independently is alkyl(1-6C),under conditions wherein said compounds of Formulas VA and IV react toform a compound of Formula VIA.
 9. The method of claim 8 wherein LvO isa p-toluenesulfonyloxy (TsO) group.
 10. The method of claim 5 whereinthe compound of Formula VIIA is prepared by alkylating purine orpyrimidine moiety B as defined in claim 1 in the presence of alkalimetal hydride or carbonate with an (R)- or(S)-2-O-dialkylphosphonylmethyl compound of the formula:

substantially free of its enantiomer wherein LvO is a leaving group andR is independently alkyl(1-6C), aryl or aralkyl.
 11. The method of claim10 where said alkali carbonate is cesium carbonate.
 12. The method ofclaim 10 wherein LvO is a p-toluenesulfonyloxy (TsO) group. 13.9-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-dimethylaminopurine. 14.9-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-diethylaminopurine. 15.9-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-butylaminopurine. 16.9-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-(2-butyl)aminopurine. 17.9-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-cyclopropylaminopurine. 18.9-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-cyclopentylaminopurine. 19.9-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-cyclohexylaminopurine. 20.9-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-pyrrolidinopurine. 21.9-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-piperidinopurine. 22.9-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-morpholinopurine. 23.9-(R)-(2-Phosphonomethoxypropyl)-2-amino-6-benzylaminopurine. 24.9-(R)-(2-Phosphonomethoxypropyl)-8-azaguanine. 25.8-(R)-(2-Phosphonomethoxypropyl)-8-azaguanine. 26.7-(R)-(2-Phosphonomethoxypropyl)-8-azaguanine. 27.9-(R)-(2-Phosphonomethoxypropyl)-8-aza-2,6-diaminopurine. 28.8-(R)-(2-Phosphonomethoxypropyl)-8-aza-2,6-diaminopurine. 29.9-(R)-(2-Phosphonomethoxypropyl)-6-mercaptopurine. 30.9-(R)-(2-Phosphonomethoxypropyl)-N1,N6-ethenoadenine.
 31. A compoundselected from the group consisting of9-(R)-(2-phosphonomethoxypropyl)-2,6-diaminopurine and the 8-aza analogthereof.
 32. The compound of claim 2 wherein B is a adenine.
 33. Thecompound of claim 1 wherein B is purine substituted at the 6 positionwith amino, hydroxy, alkoxy, alkylamino, dialkylamino, aralkylamino,azido, mercapto or alkylthio.
 34. The compound of claim 33 wherein the 6position is substituted with amino or azido.
 35. The compound of claim33 or 34 wherein the 2 position is substituted with amino.
 36. Thecompound of claim 1 wherein is B 8-azapurine substituted at the 6position by amino, halogen, hydroxy, alkoxy, alkylamino, dialkylamino,aralkylamino, benzoylamino, azido, mercapto or alkylthio.
 37. Thecompound of claim 1 wherein alkyl is methyl or ethyl.
 38. The compoundof claim 1 wherein B is adenine, 2,6-diaminopurine, 2-aminopurine,hypoxanthine or xanthine or the 8-aza analogs thereof.
 39. The compoundof claim 1 wherein B is substituted with amino, alkoxy, alkylamino,dialkylamino, aralkylamino, benzoylamino, azido, mercapto or alkylthio,and wherein alkyl independently is C3, C4, C5 or C6 alkyl.
 40. Thecompound of claim 39 wherein alkyl is 2-propyl, n-pentyl or neopentyl.